The ones on their standard download page are not compatible with Xen kernels according to the release notes. The ones to be used for Xen kernels on x64 is this one: http://www.3ware.com/KB/article.aspx?id=15257
That only has a zip file, not an image file.
Russ
http://www.3ware.com/KB/article.aspx?id=15257 is the files that go on a driver disk. I just dl'd it and opened it. I know there is a way to use a driver disk from other media, but I can't find it, and I'm sure someone on list will remember how.