A hardware questionnaire

Another one?

Yep. A while back I bought myself a medium end computer with the intent that I was going to ween myself away from PC games and be done with them once and for all. I'm certain plenty of you know how futile that attempt is, so now I want to upgrade this sucker without breaking the bank. The computer I bought is an E-Machines T6420.

I'll wait for you to quit laughing, so no hurry.

Anyhow, I've gathered together a list of things I need to get this thing in motion, and I'd just like some opinions on whether or not these are quality components or not. My plan is to be able to play games like F.E.A.R. and Quake IV. I know the machine they're going into will be the weak link, but such is life. Overclocking isn't going to be a concern of mine, so no need to factor that in. My spending limit will be $350, shipping costs included. Fire away!

The computer itself is built with this:
AMD 3400+ 64-bit processor
2x512 PC3200 dual-channel RAM, two slots free
200GB ATA Seagate HDD
Hipro 250W Power Supply

What I'd like to add are these:
PNY 256MB Ge-Force 6600 PCI-E card - $132.00
Antec 350W SmartPower PSU - $38.00
2x Corsair Value Select 512MB PC3200 RAM - ~$100.00
Logitech Razor Copperhead mouse - $46.00
Total: ~$316.00

Jam it back in, in the dark.

Is there a specific advantage to getting a higher wattage PSU save the ability to add more power hungry components to the mix? Do higher end cards need 400+ watts to run properly?

All in all, seems like my original setup isn't as lacking as I thought. Any other recommendations on a mouse? I like the concept of having seven buttons within easy reach. My cousin has one for his rig and it proved invaluable when he went through Doom III.

There's nowhere I can't reach.