Sounds like Linux boots ok, but just doesn't seem to be able to set the screen type/geometry correctly..
I'd suggest you try letting it boot, then switch to a text console with ctrl-alt-F1 for example and see if you get a nice clean console to work with, and work your way through there to set up a new monitor. Since you didn't mention what distro you use I won't be able to get more specific. Perhaps some guru might be able to assist here too.