Dear Samir
For these DOS products, it is more important to ensure that your version of ACCPAC Plus Windowing System Manager is compatible. We suggest WSM7.0 w/SP2, however, more information on this can be found on the www.PlusCommunity.com technical discussion forum. Perhaps WSM 6.5 is ok too - but I cannot say for sure.
Otherwise, I have not heard of any issuess running QR6.5A and QIP6.5A/6.7A with W2K O/S. I am running that myself, and have had no problems. (I am also running WSM 7.0 w/SP2 though).
Good luck!
Regards,
Softrak Support