Minimum system requirements to play minecraft on decent settings smoothly?

My nephew is in love with minecraft he has been playing it on my rig quite a bit,and well he is home schooled and he has been having trouble reading cause he has dyslexia,and he gets frustrated and quits really trying.

Well to motivate to try harder i told him i would build him his own pc from some old parts i have lying around,and i would like to know what would you guys consider to be the minimum system requirements to play minecraft on decent settings smoothly?

Dual core processor 4gb of ram and a hd 5450 / gt210 or better I have tried my self and that is what I found

Decent processor and lots of RAM. The GPU isn't very important for minecraft.

To run with little to no lag you need a Pentium (ivy bridge), 4 GB of RAM  and a Radeon HD 4250. Then again, this is to run at basically no lag with fancy settings with a bit of head room. Alternatively, you could also use Intel HD 4000 with a higher up processor (Which I recommend considering minecraft uses only one core and performs solely on architecture and clock speed).

thoughts on GPU

I bought last year a HD6450 from msi for <$50 and it runs minecraft @ max settings (no optifine) @ a solid 30fps

so I'm thinking a simple APU like the A10-5800k will do just fine. If you think your current stuff is too old or not good enough.

Ok i looked at my old parts,would this work & at what setting would this play with out lag?

AMD Athlon X2 5600+ 2.8Ghz,4GB DDR2 667mhz,and a GT240 1GB and an old IDE drive

i think that GPU is fine, but the CPU is pretty low, lower setting MC it might work but i would spend a little to upgrade and furture proof it a little more than what it is.

keep the 240 though

Ram shouldn't matter my old desktop has 8GB of ddr2 667mhz with the 6450 and it runs MC just fine (close to max) NOTE: the cpu is the phenom 9150e

Put it together and try.

But yes, Dont' take our word for it, Test it out for yourself and see how it runs.

i've played decently on a dell optiplex with a 32bit os.....

I have managed to play Minecraft on an AMD Sempron 140, 2gb of DDR2 ram and an onboard NVIDIA GeForce 7025 without the FPS going below 35.

If you were to get a Sempron 140/145, I would recommend an AMD Radeon HD 5450 as a budget GPU to go with it as it will run Minecraft without a sweat.

keep the 240gt its on par with a 5670 (or 5570, too lazy to relook up benchs) which is better than the 5450 or anything else anybody has mentioned, a sandy or ivy pentium dual core class CPU will do nicely for mine craft, if you have like 200 bucks grab a cheapo 1155 board, 8GB of 1600 9-9-9 ram and a Ivy pentium dual core, a ivy i3 will be the next best thing

trainer games don't listen to njm, you'd be able to play with that most likely with over 60 fps, even with 3d on.

A number of systems I've played on:

  • Thinkpad T42: Pentium M 1.7 ghz, Ati Radeon Mobillity 7500 32mb, 512 mb DDR ==> unplayable, in large areas 3 fps due to memory was playable at 15-30 fps on LAN with 2 people. Most likely the memory was the culprit, not the video card, I can't confirm though not investing in it.
  • Thinkpad T61p: Core 2 Duo T7700 2.6 ghz, nVidia Quadro FX 570m 256mb, 3gb DDR2 ==> fully playable >60<100 fps while running a server with a 2gb limit (java32bit only uses 1 gb anyway).
  • Core 2 Duo E7300 Desktop, ATi HD 3850 512 mb gddr3, ATi HD 4870 1GB gddr5 both 256bit, 8GB DDR3/2GB DDR2 ==> Fully playable while running a server with 4gb ram. The ddr2 and 3850 setup worked just as well except it lagged a little more on OptiFine shader mod due to fewer RAM. Usually sits at 130 fps, 2gb had around 100, must be the video card as well.
  • Pentium 4 3Ghz Desktop, Ati xpress 200 integrated (a sort of x1300 implementation, weak), 2GB DDR2 ==> Playable (>25<50 fps) with noticable slowdowns in big areas. 
  • Celeron Northwood 2.4 Ghz, nVidia Geforce 4 Ti 4200 128mb/ ATi 9550 128mb, 512 DDR ==> Playable in small areas, lag when the world changes, RAM insufficient.
  • Dual Pentium 3 1Ghz, same video cards as above, 2GB SD-RAM ==> Playable until building too much 32 fps, drops to a constant 16 (1ghz is insufficient 1ghz p3 is 1.6ghz p4 equivalent, pentium m and tualatin pentium 3 are a lot better than this, 
  • Idem above, OC @ 1.15Ghz, SD-RAM at 150 ==> 3 min 5 fps max increase
  • Pentium 3 933Mhz, nVidia Geforce 2 MX 440 64 mb, 512MB SD-RAM ==> Not really playable 10 fps, even on Tiny render distance (same case as with my T42)
  • Dual Pentium 3 1Ghz, (Ati rage II or pro agp, 4 or 8 mb i forgot, just for fun, could run half life 1) ==> 15-20 fps unfortunately, I'm sure if I had a Voodoo 3dfx (or 2 in SLI) I could run it with a Tualatin Pentium 3 better than most integrated graphics and low end video cards.
  • Acer laptop, i3 370 2.4 Ghz, nVidia 540m GT 1GB DDR3, 3 GB DDR3 ==> Very playable with dedicated video (I usually keep vsync but i've seen it as high as 105), integrated is playable but around 30-45, gets laggy in time.

I'd love to see minecraft desktop version on a raspberry pi or similar boards, that's like a 100 times smaller than small office pc cases and starts to be as powerful (risc though).

That setup is arhisufficient for Minecraft and a lot of other games, newer games (>2012, they're crappy (most of them) anyway, imho) not so much, though there is no hard bottleneck since the gpu is paired well with the cpu.

Read through this for more benchies http://www.minecraftwiki.net/wiki/Hardware_performance

i found this:

 

Ubuntu 12.04 (32Bit) - AMD Athlon X2 5600 @ 2.9Ghz - Nvidia GT 9600 512MB - 2GB DDR2 800Mhz - 160GB 7200rpm (Seagate) - 1440x900 - 1.4.4 - windowed: 60-80 fps, maximized 50-60 fps - Perfectly playable.

Your video card is quite a little better and you have 4gb, run java64 ver then and he'll/you'll both be fine.

to be honest the parts you have there for minecraft are just fine, my gf plays minecraft on a asus a6ja 1.8ghz centrino dual core with 2gig of 667mhz ddr2 RAM, and a ati x1600 with 256mb VRAM, with a 160gb IDE drive. and it runs just fine, and that laptop is nearly 8 years old lol