I'm getting used to Win 7. However, the computer now seems to hang slightly when I'm opening a new programme, or even when I'm opening one of the drives in Windows Explorer.
Have you checked your power save settings ? The default in Windows 7 is to power down disks that have not been used in a while and if this is the case there will be a noticeable lag as the drive spins up to speed before it can be accessed. I believe the default value for this is 20 minutes in high performance but will be reduced in other settings.
You can check this by typing power at the start menu, select change power save settings, adjust the plan with the advanced properties to see the value.
Also the value you quote for disk sizes in MB are you sure you dont mean GB ?
Another performance tip would be to move your swap file from your C: drive to another physical drive if you have one - you would probably want your pet guru to do this for you.