I've been using both VMWare Server and Virtual Server 2005 for quite a while now, and while each has strengths and annoyances, I like VS2005 better, mostly because I've written a bunch of PowerShell cmdlets to manage it. However, I needed to deploy a few 64-bit Longhorn images this week, and because VS doesn't yet support 64-bit guest VMs, I had to go back to VMWare.
Trammel runs our test lab, and he provisioned a couple of 64-bit images for me running on VMWare Server. I hooked up the WS2008 RC0 ISO image and installed without any difficulty (other than dealing with the impossibly bad KVM virtualization when the VMWare Tools aren't installed in the image). But when it came time to configure the networking in the VM, there were no NICs to be found, even though there was one configured for the VM.
I spent about half the day trying to get the problem sorted out.
The trick is: BEFORE you install WS2008, edit the VMWare configuration file for your VM and add the following line:
Ethernet0.virtualDev = "e1000"
Then start the VM and install WS2008. WS2008 will then detect the NIC properly. I don't know what the issue is, but I guess that VMWare can present different kinds of virtual NICs to the OS, and the "e1000" NIC is something that WS2008 recognizes.
If you do this AFTER you've installed WS2008, it won't work. Not sure why that should be the case, either, but there it is.