I'm not sure about the mouse stuff (I don't use X11 within a Linux VM...just run stuff against the host machine's X11.app), but the CPU hogging you're seeing is normal. If other people aren't seeing it on Fedora Core 6, they aren't looking.
The CPU difference between distributions when idle is almost entirely the result of the HZ setting in the kernel, which is basically how many times per second they wake up to see what task to run next. It's a compromise between responsiveness and battery life. RHEL4/CentOS 4 has (if I remember correctly) HZ=100. RHEL5/CentOS 5 has HZ=1000, so it uses about 10X as much CPU/battery life. Fedora Core 6 also. You can easily measure this by running something like
$ fgrep timer /proc/interrupts; sleep 10; fgrep timer /proc/interrupts[/code]
then subtracting the first number from the second.
If you're feeling up to it, you can download and recompile a new kernel on any distribution. In particular, very new kernels support "CONFIG_NO_HZ" / "dynticks" / "tickless", which totally removes this compromise. They wake up when they need to, not at a fixed interval. I've done it, and my Linux VM uses much less CPU time now. There are a few other things that wake up more often than they should (like the VMware Tools 11 times per second...grr), but still the difference is night and day.
Fedora 8 (and likely the next releases of other distributions) will be tickless without having to replace the kernel.
In fact, you can even try running their Fedora 8 development kernel on Fedora Core 6. I haven't tried it myself, but I'd expect it to work.
i386: http://download.fedora.redhat.com/pub/fedora/linux/development/i386/os/Fedora/kernel-2.6.23-0.45.rc0...
x86_64: http://download.fedora.redhat.com/pub/fedora/linux/development/x86_64/os/Fedora/kernel-2.6.23-0.45.r...
I have wasted a few days on this now. VMWare I hoped would make it easier (I didn't have any hardware hassles at least, but its all moot if its not usable).