Welcome to SF, Space4092. First, please complete your system specs.
Did you install any memory before the upgrade? If so, sometimes you need to install in pairs.
When you try re-installing the OS, do you get past the bios screen? At what point does it lock up?
Do you have hard drive activity?
Can you swap out your graphics card?
Can you boot up on a live operating system DVD (e.g., Knoppix, Ubuntu Live, BartPE, etc)?