New video card with a power restriction

I'm a new poster to the forum, although I read them every day. This is simply the first time I've required asking a question. Ok, enough background.

My situation is: I have a decent (in my opinion) system except for the video card. I am not a huge gamer, although I have been enjoying NFS: Carbon, and may be playing more games in the near future since I'm finally out of college. I have been considering replacing my vid card soon to get higher FPS (at 1024x768, the native res of my Samsung LCD) and higher settings (turning on AA/AF). I have been considering the following cores:
7600GS AGP
7600GT AGP

Here's the situation though:
Sony sucks and makes their own stupid proprietary power supplies and replacing the PSU is not an option. The power supply (250W) has worked flawlessly with the setup (and I've even had up to 4 HDDs at once, and all PCI slots filled, USBs filled) and has never choked.

I went onto eXtreme Power Supply Calculator Lite v2.5 and entered my current configuration, it came up with 278W (obviously higher than the rating for my PSU). Then I put in the same thing except for a 7600GS in place of my 5200, and it came to 271W.

Ok, finally to my questions: Does the 7600GS actually use less power than my less-than-adequate FX5200?
Can I trust that my PSU will not choke with the 7600GS in there?
Should I consider the 7300GT or any other card because of the power restriction?

Sorry about being so word-y, I simply don't want to purchase something I can't use.
Thanks in advance for your help.

Should I go with MSI -
http://www.newegg.com/Product/Prod [...] 6814127219

Or EVGA -
http://www.newegg.com/Product/Prod [...] 6814130076

Same price, same proc.

On a side note, is my setup simply showing up once? I copy/pasted it into my signature. Please let me know if it's showing up twice, or if there's a way to display it, and delete it out of my signature and leave it in my system setup profile box.