Is my cpu or mobo bad?

I have an Emachines T2825 with the following:

Amd Athlon XP 2800+ cpu
NVIDIA nForce 2 chipset
120GB HDD
48x Max. CD-RW Drive,16x Max. DVD,3.5" FDD,8-in-1 Media Reader
NVIDIA GeForce 4 MX graphics
nForce 6-channel Audio
10/100Mbps built-in Ethernet
56K ITU v.92-ready Fax/Modem

Here's the problem.....I've installed a new power supply. It works fine. I have tried using the VGA port for my monitor. I've installed an AGP video card. But I still get absolutely nothing on the monitor. Can't even get into cmos without a monitor.

I'm wondering if the old power supply fried the mobo or cpu?
Any suggestions/recommendations would be greatly appreciated!