Something is not installed correctly because this OS is not known for being slow and your specs are plenty fast enough for 7.
Could you check device manager for any driver issues (yellow exclamation points)?
What chipset are you using?
What video card are you using?
How much and what type of RAM?
Have you checked for laginess without VMware running?
Sorry for all the questions but that is the nature of troubleshooting: asking questions until one leads to an answer.
I'm going out on a limb and assuming that to be 8GB of RAM not MB. When you installed did you have all that RAM in place 7 is VERY touchy about RAM being cleanly seated you could try re seating it all and after all else fails i would re install 7 with the minimum RAM i could and the re install it after.
In your hunting check Task Manager for CPU spikes and what they are attached to. Also look at your memory usage and page faults.
Any time your running anything inside a virtual machine your going to get a performance hit. If your noticing a hit larger than you experienced in vista then there is a problem with your virtual machine application. I would check with VMware about this issue perhaps there is a version more compatible with 7 64 bit? It could be that you have to much RAM allocated to VMware not leaving enough for 7, that would explain your disc access as well.
Open task manager to the processes tab, (be sure to click show proceses from all users).Click the column that says CPU to order the processes from the highest to lowest and when you see what process is using the most during the spike.
I spent the whole day yesterday installing/uninstalling between W7 and Vista. In the end, I do not why two image software I use do not work with W7. I just dont know what it is. But the rescue cd work on my laptop and the other desktop(both on W7). My drive on this machine is a blu-ray dvd burner combo.
Anyhow I am almost back at where I was from my first post.
Everything is working fine so far.
I am leaving doubt that any Microsoft softwaree had anything to do with this lag.
The only thing different that is installed on this machine compare to the other 2 machine that also run in W7 with the same image is :
* FileZilla Server
* Macrium Free
* Gizmo drive
SO, my other two machines are running fine without any lag because these 3 software are not installed.