Unless I'm overlooking something, any modern day power supply will work....They might have more plugs than you need, but the basics are there. I don't know how much power you need, but I'd assume with an old system like that, you'd probably be ok with 400-450W. However, if you want to future proof your investment, get at least a 550W, so you can re-use your new power supply if you upgrade.
As for the RAM. your post says what kind of RAM you need: PC3200
It's hardly worth buying new, as you can probably find somebody giving that stuff away, but if you decide to buy new, here's 512MB for $24:
http://www.ncix.com/products/?sku=28...acture=Buffalo
But seriously....find somebody that's willing to give you that stuff for free...lol