vista winsxs folder eats disk space [duplicate]

Possible Duplicate:
Why does the /winsxs folder grow so large, and can it be made smaller?

My machine has been running Vista Ultimate 64-Bit for about two years now. ServicePacks SP1 and SP2 are installed, too. The system partition has a size of 55 GB, which should be quite comfortable under normal circumstances, but about 40GB (no typo) are used by the Windows-Folder, especially the subfolder winsxs, which takes about 35 GB. I have already uninstalled as many programs as possible and did run compcln.exe, to reduce it, but this only gained 2-3 GB.

What can I do to clean up without risking system stability? I'm a software developer and this is my daily work environment, which means - I can't risk to get strange side-effects from blindly deleting stuff. - You can maybe deduce some typical usage patterns from this information.

Any suggestions?

Solution 1:

You can't delete this folder. It's the assembly cache.

From TFA:

The Winsxs folder, stores multiple copies of dll's in order to let multiple applications run in Windows without any compatibility problem.

Link is: http://www.winvistaclub.com/f16.html

EDIT: compcln.exe, part of Vista SP2, allows you to remove RTM and SP1 files from the cache, but it will not allow you to roll back to a previous version if you wanted to. The Service Pack Clean-up tool is a replacement of Vsp1cln.exe from Vista SP1 that did much the same thing. See more here.