yes the vista drivers usually work because win7 is merely a refined version on vista. there are times though when the drivers are not compatible do to said refinements. We've all been running win7 for a while now I got lucky with drivers a few of my friends had to upgrade odds and ends.
As to virtulization, the first requirement is that your hardware supports it...... there are a ton of people in this and other forums who can't run xp mode because their hardware doesn't support virtulization. Doesn't sound like it was designed for hardware compatibility to me.
And the second runner up for why people can't run xp mode is as you stated only the business, enterprise, and ultimate versions supports it. Though I'm sure with a little effort you could work around that one using VMware or similar program.