Ubuntu cluster of resources?

[Bart Silverstrim]

Is there a way to take a group of machines running Ubuntu and have them 
act as a virtual machine, with one IP?

I was looking for a way to have hardware redundancy for drive storage 
and accessibility of applications while stuck on a budget.  As a test of 
feasibility I'm already setting up a system of VMWare servers where 
there are a couple machines running Ubuntu with VMWare server and a 
central NAS to store snapshots of tarred/gzipped drive images so if the 
hardware died (or a virtual machine goes wonky) I can bring up another 
system with VMWare on it and copy the tarred image over and bring up the 
virtual images again to at least keep the virtual systems running while 
the non-virtual system is repaired.

I was hoping there was a more automatic way to do this, using machines 
tied into a cluster of sorts so that one IP could access a "virtual 
computer" running vmware and storage, if not memory/processing 
resources, could be shared and if a machine died I'd just replace that 
machine and things would keep going.

Anyone know what I am describing and/or what options are available when 
all I have access to are some older workstations, a switch or two, and 
some time to configure Linux on them? Like I said...specialized hardware 
is a no-go for the budget, so I'd be interested in hearing what options 
there are.  Some virtualization technologies, like KVM, aren't feasible 
because some of the images I'm running are using Windows.