An SSD is the single most efficient and powerful parts upgrade for PC's in the last 5 years, but for gaming, it doesn't make much difference at all. Gaming needs CPU and especially CPU power, not much else, most games are still 32-bit, so any individual gaming application can only address 3.6 GB of RAM, even on a 64-bit OS, so you don't even need more than 4 GB of RAM for any gaming machine. Business and day-to-day use however benefits greatly from SSD's, most business and multimedia consumption applications don't need much CPU power and only limited GPU functionality. Multimedia or 3D technical production applications benefit enormously from multiple SSD's and more RAM and a strong CPU and GPU. So decide which applications you're going to run, if it's only games, you really don't need an SSD.
if your not worried about speeds than you should invest money elsewhere unless you have mechanical drives crashing alot and are tired of that, otherwise theres not really a need for you to buy a ssd. A ssd does not however increase speeds of all programs only that of which are one that drive so if you have a standard mechanical drive as a mass media drive using a ssd would only benefit programs on it so if you are getting one i would get one that has enough space to put all your programs and os on. If your looking for one i recomend ocz as i have never had a problem with there drives (i have used 3 in the last year).
SSD's are more of a convieniece or luxury if you will. The real cost is - time. If all you do is game on your system and you have time to "spend" downloading and uploading small files here and there then an SSD would be overkill. Although, if you work with video files H.264, AVCHD, RAW files, large format Codecs and you would need a way to "save" time. This is where SSD's are most beneficial, because of their read and write speeds. Anything less is just a luxury.
You can allways grab a 60gb sdd and just use it for the os and keep everything else running from standard harddrives.
I have a 60gb ssd (Kingston Technology 60GB Solid State Drive V300) that runs windows and its day to day applications/softwhere and x2 500gb WD drives i store and play my games from (there set in raid 0 you dont have to do that)
This realy just speeds up windows more than enything else and i like a fast snapy sistem so its not that expencive 60gb ssd is around £40 (it will be even chaper in the US)
Its more down to budget and personal preference at the end of the day
I actually just installed my second SSD today. No regrets what so ever. It also makes you system safer considering you dont have less moving parts in your computer. Because if you HDD explodes and peices go everywhere well, thats a $60-$100 for an SSD than a $800+ cost for a new PC.
You should really be asking us why you should not go SSD.
In pretty much all gaming rigs the HDD speed is the bottleneck (slowest part of the system) so when you upgrade your system you should always start with the bottleneck. Your system can only be as fast as it's slowest part, there is no use in getting a faster GPU/CPU/RAM when they have to wait for the HDD to finish doing what it should be doing.
edit: should point out I have an OCZ and kingston SSD in my desktop and notebook and I have also worked with intel and samsung drives never had any problems with them.
My gaming buddies have Intel 520 120GB in their gaming rigs.
SSDs are fast and quiet. Ideal for laptop upgrades due to lower powerconsumption compared to standard harddrives. I only use SSD for operating system, drivers and various programs. Games and personal files will be stored on harddrives.
If you like a cooler, quieter and faster storage device then you get an SSD. I'm just now experiencing my first SSD, I will NOT go without one from now on.