Yeah, this is where the upgrading gets complicated for the gamers....
As "tweaking" gamers still using many legacy tools introduced in the early parts of this decade for improving our sims and games, we have to be flexible in our OS upgrades. We can ill afford to just go whole-hog and dump everything into newer OS's and expect it all to work as always. This is where the merits of building a dual-boot or even triple-boot OS structure comes into play for maintaining the usefulness of our older tools like Mdlc and others.
We have to plan wisely in our upgrading. If we elect a new 64-bit system upgrade for improved gaming and GC performance, we'd better keep a 32-bit system either on another drive, another partition or another computer altogether for crunching design or tweak work with legacy programs. Its the only way to be sure that the workshop remains productive....