| Table 1: Feature Comparison | ||
| Feature | Microsoft Virtual Server 2005 | VMware GSX Server 3.1 |
| Supported host OSs | Windows 2003, Standard, Enterprise, and Datacenter Editions; Small Business Server (SBS) 2003, Standard and Premium Editions; Windows XP Professional (for non-production use only) | Windows 2003, Enterprise, Standard, and Web Editions; Windows 2000 Advanced Server; Win2K Server Mandrake Linux 8.2 and later Red Hat Enterprise Linux AS 2.1, ES 2.1, and WS 2.1 and later; Red Hat Linux 7.1 and later SuSE Linux Enterprise Server 7 and 8; SuSE Linux 7.3 and later Turbolinux Server 7.0 and later; Turbolinux Workstation 8.0 |
| Supported guest OSs | Windows 2003, Standard, Enterprise, and Web Editions; SBS 2003, Standard and Premium Editions;Win2K Server; Win2K AS; NT Server 4.0 with Service Pack 6a (SP6a) | Windows 2003, Web, Standard, and Enterprise Editions; SBS 2003; XP Pro; XP Home Edition; Win2K Server; Win2K AS; Win2K Pro; NT Server 4.0 SP6a; NT Server 4.0, Terminal Server Edition with SP6a; NT Workstation 4.0, including SP6a; Windows Me; Windows 98; Win98Se; Win95; Windows for Work-groups 3.11; Windows 3.1; MS-DOS 6.22 Mandrake Linux 8.0 and later Red Hat Linux 6.2 and later; Red Hat Enterprise Linux (AS, ES, and WS) 2.1 and later SuSE Linux 7.3 and later; SuSE Linux Enterprise Server 7 and later Turbolinux Server 7.0 and later; Turbolinux Workstation 8.0 Novell NetWare 4.2 FreeBSD 4.0–4.6.2, 4.8, and 5.0 Sun Solaris 9 OS (x86 Platform Edition) and later |
| Maximum number of processors | 32 | 32 |
| Maximum RAM per server | 64GB | 64GB |
| Maximum RAM per VM | 3.6GB | 3.6GB |
| Graphics support | VGA and SVGA (must install Virtual Machine Additions) | VGA and SVGA (must install VMTools) |
| IDE drives | 4 | 4 |
| ISO CD-ROM support | Yes | Yes |
| SCSI devices supported | 28 (7 for each of 4 adapters) | |
| 21 (7 for each of 3 adapters) | ||
| Diskette drives supported | 1 | 2 |
| Network adapters supported | 4 | 4 |
| Serial ports supported | 2 | 4 |
| Parallel ports supported | 1 | 2 |
| USB ports supported | No | 2 |
| Sound support | No | Sound Blaster emulation |
| VHD types | Dynamically expanding, fixed-size, differencing, linked | Virtual, raw |
| Ability to undo VM changes | Yes (undo disks and differencing disks) | Yes (snapshots) |
| Virtual network types | None, internal, external | None, host-only, bridged, NAT |
| Built-in DHCP | Yes | Yes |
| Secure Sockets Layer (SSL) console support | Yes | Yes |
| Scripting API support | Yes (COM) | Yes (Perl and COM) |
| Requires IIS 6.0 | Yes | No |