Can a Dell XPS 400 run a 64-Bit Operating System?

Im just wondering if it is possible to run a 64-bit operating system, such as Windows 7 on a 2005 Dell XPS 400 desktop?

It wont recognize or read a 64-bit Windows 7 Install/reinstall Disc, but apparently I successfully installed Ubuntu 64-bit version and it was working. 

Seems to only work loading off the CD rom drive instead of the DVD-RW drive. Is it possible its not set up correctly in the bios?