I run mine (full registered hex can USB) on a HP tc1100 with 1.5gb processor, 40gb hard drive, XP SP3 that has 30gb of it's memory taken up by elsawin, etka, auto data and thousands of fault logs yet it still performs flawlessly. Only time it's a little scetchy is on late can bus or new UDS vehicles where the info exchange causes the cursor to have a slight delay.
We also have a full version of VCDS on our VAS6150 panasonic toughbook but the software clashes and doesn't run very well together, hence we now use another laptop for it.