Inspiron 530 PSU upgrade question.

Hey. I have recently purchased a dell inspiron 530 desktop with the Intel® Core™2 Duo processor E7300 (3MB L2, 2.66GHz, 1066 FSB). Which comes with a 350 watt PSU. I'm going to upgrade the computer with a new video card and perhaps additional RAM in the future and am concerned about the low wattage of the PSU. I would like to know if anyone knows of a replacement PSU that I could buy for my computer that they know would fit in the case and not fry my mobo. (I've heard dell is a prorietary distributor or something like that, meaning that sometimes if you don't buy dell-specific equipment, it doesn't work in your dell computer.Worst case scenario, your mobo gets fried.)

I'm basically looking for 400-500 watts. No need going overboard with 800 or something. I just don't know what kind would work, or even fit, in my computer. Mine is not a slimline version. Just regular. I'm pretty sure it takes an ATX type power supply, but like I said, I don't know what would fit or work. I'd hate to buy one not manufactured by dell and end up frying my new comp. That's a surprise I definitely wouldn't want.

All responses are appreciated. Thanks.