A comparison of VMware, Microsoft Hyper-V and Xen.

	VMware	Microsoft	Xen
Product URL	VMware.com	Microsoft.com/virtual server	Xensource.com
Free server product	VMware Server	Virtual Server 2005 R2, HyperV Win Server 2008 64 bit	XenServer Express, (Enterprise 30 day eval.)
Paid server products	Infrastructure v3.5 (Starter, Standard, and Enterprise)	None	XenServer Standard, Enterprise, and Platinum Editions
Pricing range paid product	$1640 for two CPUs, includes 1 yr. support contract	Free or included in Windows Server 2008 (64 bit)	$600 - $5000 plus support contract
Host OS (if any)	Server: Windows Server 2003, various Linux Infra v3: bare metal	Windows Server 2003 R2, 2008; XP Pro SP2 or Vista for testing purposes only	Bare metal
Management tools	Lifecycle Manager, VMotion, Storage Vmotion	System Center VM Manager	XenCenter Management Console
Embedded hypervisor product	ESXi supports both AMD and Intel chipsets	None*	Yes
Advantages	· Over 700 pre-built appliances · Widest selection of guest OS support · Wizards galore for install aids	· Can run on any IE browser with Internet access · Less expensive option · Easy cloning of VM images · Familiar UI	· Open source solution that doesn't require any host OS · Lower cost
Disadvantages	Confusing array of pricing and configuration options (2 CPU minimum pricing)	Limited pre-built VHD appliances and just of MS server products	Limited Windows guest OS support