I have tried Ubuntu before and it did not play nicely with Microsoft Virtual PC. Is it possible to do a dual-boot between Ubuntu and Windows XP? Also, I thought Ubuntu was Linux based and not Unix based. Can a Unix clone really as good as the real thing?
If you want the real thing, go with Solaris. It's SVR4 and XPG4/6, and certified UNIX(tm). It also ships Gnome next to CDE. At least in the Solaris Nevada development builds, which are pretty stable, I might add.
So yeah, if you want to continue with what you're used to, go with Solaris x86. Preferably, you should go with Solaris Nevada, which are the development version and technology testbed for what'll become Solaris 11. Don't be mistaken by "development version",
even the bleeding edge Community Edition is pretty stable, but going with the Development Edition gets you the extra assurance.
If you want Gnome 2.20, you need to go with Solaris Express CE snv_75 or wait for Solaris Express DE snv_80. All builds before snv_75 ship with the previous release.
Another idea would be to wait for Project Indiana March release. But that project focuses on giving the Linux people a nice and easy entry in the Solaris world, as such it's bash, GNU userland and things like that. Though these things will be user controlled
from within the installer, so you can switch to between GNU, SVR4, POSIX and whatever that other was at install time.