I'm always finding new uses for VMWare. I run XUbuntu on my XP machine at work, mostly for interacting with Solaris servers.
I also run Solaris in a VM so I can
test upgrade procedures before destroying one of my servers. If I make a mistake, I can delete the current VM's directory and restore one I've got backed up.
We just bought a VMWare server for our test lab so we will not need to maintain a dozen different boxes each with its own OS and application stack.
Is this typical of FF 1.5 on Linux?
Definitely not. I used FF 1.5 on Ubuntu for a while and it was always stable.
On VMWare?
My VM's are pretty stable. I've never seen a Firefox problem, though as I indicated above, I'm not really using them for browsing. I just checked my XUbuntu VM (installed from the Fiesty CD) and it has FF 2.0.0.3. How old is the VM you are using?