If you're REALLY strapped for cash, your 250W will probably hold out for a while, but not long especially if you're running a newer processor, big hard drive and lots of fans. I learned this lesson the hard way, constantly encountering blue screens, corrupt files and registry entries, random lock ups and reboots. I finally swapped out the PS, and voila! I haven't had so much as a hiccup since I did it. Check out this link.
http://www.pcpowerandcooling.com/pro...lies/index.htm