After I complete the installation, it reboots and shows the cursor behind a black screen and then the screen goes blank, does not receive signal from the computer. Help me before I return it?

Here's my OS's info:
-Intel Celeron 1.7ghz
-640MB RAM
-RADEON 9600

PS. I ran WGA before installing it and it says I was go for Business but not Ultimate which I'm installing but why won't even it show?