how do you mean it ran slow? any particular apps/ all apps or disk access?
I use parallels with my boot camp partition and it seems ok.
Not blistering fast I might add, but maybe i dont have it setup correctly?
I currently have a macbook with 3 gig ram and the xp setup currently uses 768k.
I only use MS office (mainly excel and outlook) and some avaya softphone software in the xp window and both xp and osx used to grind to a halt when I had only 2 gig ram and allocated 1 gig to xp and 1 gig to osx.
I also have parallels set to give priority to osx as I believe this way osx can keep charge of the whole system, if I gave priority to xp, then both xp and osx may be slow when I am thrashing out some excel sheets!
I also might add that when i load up the avaya softphone app, the macbook fan seems to thrash all the time! I wish I could find a way to change that, have tried dropping the process priority in xp for that app to no avail.