6 or 7sp freewheel with 9 or 10sp derailleur?

Thanks for the replies everyone.
Really? Thats interesting to know. You managed to limit the side to side movement with the limiting screws no problem? What shifters are you using? Indexed?

Indexing was pretty easy to set up. Using 7 spd Sora (I think- they'er just labelled "Shimano") Sti's. Said it before but the shifting is clean and pretty precise - at some point I'll upgrade the bike to full 10 spd, but until I get a new wheelset and sti's this is working really well.