TheBoots,
please see the System requirements for the last Parallels Desktop 4.0 version here:
http://www.parallels.com/products/desktop/sr/
And regarding ti Parallels Desktop 3.0 refer to documentation: Microsoft® Windows:
Windows Vista® Ultimate, Enterprise, Business
Windows Server® 2003 Standard Edition SP0, SP1
Windows Server 2003 Enterprise Edition SP0, SP1
Windows Server 2003 Web Edition SP0, SP1
Windows XP Professional SP0, SP1,SP2
Windows XP Home SP0, SP1,SP2
Windows 2000 Professional Edition SP4
Windows 2000 Server SP4
Windows 2000 Advanced Server SP4
Windows NT® Workstation 4.0 SP6
Windows NT Server 4.0 SP6
Windows ME
Windows 98
Windows 95
Windows 3.11
Windows 3.1
Windows 2008 (Longhorn) is supported experimentally.
Linux:
Red Hat® Enterprise Linux 5, 4, 3
Red Hat® Linux 9, 8, 7.3
Debian® Linux 4.0, 3.1
FedoraTM Core Linux 6, 5, 4, 3; FedoraTM 7
SUSE® Linux 10.2, 10.1, 10.0, 9.3, 9.2, 9.1, 9.0
MandrakeTM Linux 10.1, 10, 9.2
Mandriva Linux 2007
Ubuntu® Linux 7.04, 6.10, 6.06, 5.04
Xandros Busines 4.0
CentOS 5
FreeBSD® Guest Operating Systems:
FreeBSD 5.4, 5.3, 4.5, 4.1
16 Parallels Desktop for Mac User Guide
OS/2® and eComStationTM Guest Operating Systems:
OS/2 Warp 4.5, 4
eComStation 1.2, 1.1
Sun Solaris® Guest Operating Systems:
Solaris 10, 9
MS-DOS® Guest Operating Systems: