Your Processor is ok
Your ram if fine... if you add 1 more gig... you will only get like 300 MB unless your runnin 64bit windows
Graphics card i recomend waiting for the 200 series or whatever its considered now for the prices to go down a little more.
I would get a good PSU. A nice PSU wont get outdated and will last a while. Its a good investment. I just bought one a few days ago and should be receiving it today...
Even if your current comp doesnt need a better PSU, at least you can throw it in your bigger and badder new PC that you build later.