Ohh...yeah you can use it for a year easy...But more than that maybe you would have to upgrade the CPU...
Well that time maybe you can look into overclocking...It would certainly increase the performance...If you would do more research on overclocking later, I think you mite be comfortable with it...
There are lots of great older games and even some newer ones that are awesome and will run nicely on your system.
You'd probably have a good experience with Half-Life 2 as an older game. I imagine Starcraft 2 and Diablo 3 will look pretty good on your system when they come out.
Crysis is not really worth the effort on that system.
You can go to Gamespot and show ALL the games listed by rating or year. Grab some demos, get a feel. Just because you don't have the latest and can't play all the latest games doesn't mean you can't have a fun gaming PC that will last you a while. Again, just pick and choose your games.
Microsoft is releasing Windows 7 RC to the public to test for free on May 5th. Why not get a copy of that for free?
I also recommend getting 4GB and using a 64-bit Operating System. You'll notice a difference from 2GB to 4GB just in basic usage. I did. You will. It shouldn't add much cost.
I should add that if your on a budget, you might wish to look around local ads and see if anyone's selling a used CRT monitor. They do have advantages in contrast, colour and viewing angle. Just an idea.
If you're not much of a gamer, and the games you do play aren't extremely demanding, consider a lesser GPU if it will let you get a better CPU. That's contrary to the advice often given around here, but the e5200 isn't all that great unless you overclock it, and 1) micro-ATX boards often aren't good overclockers, and 2) you say you don't want to overclock anyway. You might either reconsider that, and choose a full-sized ATX mobo (either P43 or P45), or get a better CPU. A screen resolution of 1440x900 (your monitor) doesn't need a high-end GPU.
What else will you be doing with this PC, and what game(s) do you play, even if only a few hours a week?