Piyush, it is a very old message with VMWare for quite some time.. refer here
I do believe they have it fixed in 5.0 Refer KB here.
For 4.1 I am not sure when they might fix it.
Also, I hit the same error messages long time in 4.0 while running vm-support itself with 3 vms of 4 GB each on a 8GB server. While functionality wise, I didnt see any issue, it is still an irritating message.. I tried to reduce the CPU reservations, and it went off
Hope that helps,
zXi