Okay...
first, yes, you can reconfigure at any time by running XF86Setup again, but you can also just edit the XF86Config file that it creates, if you're confidient with vi or emacs or something.
Second, yes, you can update X... I'm not sure which version comes with Corel, but go to
www.xfree86.org for all the info you need, as well as a link to a bunch-o-mirrors for downloading from.
Oh, I never checked, but I assume the video is onboard too, right??? You may want to think about disabling it and getting an el-cheapo video card that you know works (there's a link to the current video card 'supported' list on the X site, too!)
Hope this helps a bit.

Mike
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It is easier to get forgiveness than it is to get permission.
Lewis' Law: People will buy anything that's one to a customer...
Hurewitz's Memory Principle: The chance of forgetting something is directly proportional to... to... uh.....