....you'll be hard pressed to find one that will work. Actually, that is really good that you have that spare PSU around. Go ahead and try that, if possible. If it fits (literally), buy one just like it.
The only thing I'm afraid of is proprietary connectors. When replacing the PSU, make sure that PSU has all the plugs as your old one. If it doesn't, describe it and we can see if it is a standardized one or not.
I'm feeling hopeful that most PSU's will fit and be compatible. Looking at the connectors on your PSU (Bestec ATX-250-12V), they look good except for the HP 4-Pin video card power. That doesn't look necessary because the 8500GT doesn't require external power.
I would try the Antec, see how it works out. If it is good, then almost any PSU will do.
Hehe, Antec is a great maker. Actually the opposite is true of PSUs: smaller PSUs kill, larger ones don't.
I don't know much about computers, but I know I need to upgrade the power supply in my HP pavilion a6157c TV PC. It only has a 250 watt psu and an intel 950 graphics setup ,which I find out isn't big enough for my photo work or some gaming. I would like to put an 8500 size card in. A friend has aa ANTEC 430 watt unit sitting around. Will this be compatible with my HP ? Being almost double the size,will it screw up or fry any of the other components?