Should I get a new mouse

So I currently have a R.A.T 7. Is there a better mouse for FPS and RTS games? I change between palm and claw grip. 

Thats so subjective, you really need to try a few out and see what suits you best, rather then just pick one based on what PI setting or if its optical vs lazer. 

Personally I like the deathadder 2013 optical mouse.

It's hard to find a mouse with a good sensor and a fair amount of buttons. Though, if buttons aren't that important, look at some of Zowie's newer mice, a G400S, or Deathadder.

The deathadder is viewed as the best first person shooter mouse out there but a word of advice coming from a competitive fps gamer, if you play fine with a mouse don't switch it cuz you will end up screwing your skill.

RATs are not really good mice sensor-wise but if you can't find any faults with yours, don't waste money on buying something you don't really need. 

Currently using an old HP mouse I found in a drawer after my Gigabyte 6980X broke (my fault, it was a nice mouse, don't ask how it happened, I broke it accidentally).

The two things you should take note of:

Don't worry about INSANE DPI SWAG OOOHOOHOH it doesn't matter, if it feels comfortable, you're going to use it well.

Your mouse's performance comes from the mouse pad, you can have a mouse that's over $100 but it won't work well unless you have nice mouse pad. Spend $30 or $40 into an Artisan mouse pad and you'll be set.

Me and my HP have some years to go through before I part with it.

Eat your greens, buy a good mouse pad.