Did you make a typo in the subject or in the body? If it is Server 2008 you are talking about I can confirm I had the exact same observation and might have found a solution for it. I changed the host memory setting to "Fit all virtual machine memory into reserved host RAM" and has not seen this problem since. Which is really weird because the host swap was hardly ever used anyway, max 70mb.
I actually have more or less the same setup as you, only difference is that host has only 4GB. My host is 64-bit Ubuntu 8.04.
My observations is that when the guest had been "left alone" for some time and you log in via RDP, the "System" process in the 2008 guest goes berserk with 100% CPU for a few minutes, although the CPU use on the host (viewed with 'top', not VMWare GUI) is minimal.
Try to disable VMware Server memory optimizations:
C:\Documents and Settings\All Users\Application Data\VMware\VMware Server\config.ini
prefvmx.useRecommendedLockedMemSize = "TRUE"
prefvmx.minVmMemPct = "100"
guest ".vmx" file
sched.mem.pshare.enable = "FALSE"
mainMem.useNamedFile = "FALSE"
MemTrimRate = "0"
MemAllowAutoScaleDown = "FALSE"
Not quite the same issue, and my hardware is far less impressive.
My host is 64 bit windows server 2008 with 3GB RAM and a 2.8GHz Pentium D processor. I have given my VM access to 256 MB of my RAM (For now) and 1 of my cores. When using my VM and performing any CPU intensive activity, while the usage in the VM may only be 30-50% on my host my CPU usage is over 80%, sometimes pegging to 100%. What's troubling is that this is TOTAL use. Both my cores seem to be getting utilised the same amount despite that the VM's only supposed to be using 1 of the 2 and the Host is doing NOTHING.