Will I need a new PSU?

Well I bought 2GB worth of ram and since my motherboard is able to support 4GB I put the 1GB I had to make 3GB of ram. Anyway, when I first installed it it wouldn't go past the motherboard screen(Where it shows the logo of the motherboard, etc) I took out my dvd burner and it started normally. I have a 500W PSU.

Specs:
AMD Athlon 64X2 Dual Core Processor 4400+ 2.21GHz
X1600 pro 512MB PCI x16 video card
3GB Ram

ok question for 2day

check the img:

http://img291.imageshack.us/my.php?image=admsl2.jpg

Point is that I'm logged as administrator.
there are no other profiles on my PC hlp? plx