Upgrading CPU should i switch out the PS?

I am going to upgrade my CPU (and mobo) to an E4300. Here are my current specs:

Socket A AMD Sempron 2800+
2 X 512 MB PC3200 RAM
256 MB 6200 GeForce (AGP)
Soundblaster Audigy 4

Other info: I use a wireless network card, 3-6 USB ports (3 are ALWAYS on), a front bay card reader. My current Power supply is 250W and has 14A in the +12V (not sure what it means but im sure its important).

Using http://www.extreme.outervision.com/psucalculator.jsp I went from 239 W (old setup) to 242 W (just changing proccessors). Would I need a new PS when I upgrade? I rather not spend the money, but if the computer won't run without upgrading I won't have a choice :x

I'll only be using this computer for 1-1.5 more years because I'll use a laptop in college so upgrading to PCI-E and DDR2 wouldn't be worth it; the benchmarks for AGP vs PCI-E and DDR vs DDR2 don't seem to far apart, and comming from my Sempron this c2d should be a vast improvement.

Thanks for the help, I can't believe I missed the sticky

I wish I could find that psu in aus, thats the one I want, but I might have to go with this generic looking one:


click, you know you want to

Well I play farcry and oblivion alot, and oblivion is what causes my problems. Cpu is at 1.8Ghz 1.1V when I play that game and that solved the problem as far as I can see. Everything else so far I run cpu at stock speed but at 1.3V instead of 1.4V. Oblivion unfortunately is rather lagged at those speeds unless I remove distant land, even with an x1950 pro. My dads conroe system runs smoother often with an x800gto, but with 2gb RAM.