Parallels supports just about every OS that can run on an x86 platform:
http://www.parallels.com/eu/products/desktop/sr/
+*Supports 32- and 64-bit virtual machine operating systems such as Windows, Linux and Solaris — not included.*+
+*Guest OS*+
+*(32-bit) Mac:*+
+** Mac OS X Server 10.5.x Leopard*+
+** Mac OS X Server 10.6.x Snow Leopard (experimental support)*+
Windows:
+** 3.1*+
+** 3.11*+
+** 95*+
+** 98*+
+** NT Server*+
+* *+
+** Server 2000*+
+** Server 2003*+
+** Server 2008*+
+** XP Professional and Home Edition*+
+** Vista Business, Ultimate, Enterprise,*+
+*Home and Home Premium*+
+** 7 (experimental)*+
+* Linux:*+
+** CentOS*+
+** SUSE*+
+** OpenSUSE*+
+** Red Hat*+
+** Red Hat Enterprise*+
+** Debian*+
+** Fedora Core*+
+** Mandriva*+
+** Ubuntu*+
+** Xandros*+
+* Other:*+
+** FreeBSD 7.0 & 6.2*+
+** OS/2 Warp 4.5*+
+** eComStation 1.2*+
+** Solaris 10 & 9*+
+** MS-DOS 6.22*+
+** OpenBSD 3.8*+
+*Guest OS*+
+*(64-bit) Mac:*+
+** Mac OS X Server 10.5.x Leopard*+
+** Mac OS X Server 10.6.x Snow Leopard (experimental support)*+
Windows:
+** Server 2003*+
+** Server 2008*+
+** XP Professional*+
+*Vistas Business, Enterprise and Ultimate*+
+* *+
+* Linux:*+
+** Red Hat Enterprise*+
+** CentOS*+
+** Fedora*+
+** SUSE Enterprise Server*+
+** OpenSUSE*+
+** Ubuntu*+
+** Mandriva*+
+* Other:*+
+** Solaris*+
+** FreeBSD 3.8*+
