The one the MS Windows Safety Center uses is extremely robust. My pc gets cleaned by several all of the time yet the MS one found 230 problems. Two pcs at work had 640 and 1270 respectfully. The cleaning scans don't last to long, however, if you do the malware scans it can take more than a day. Lasted less than an hour on my pc but over 24 hours on slower work machines, so you may only want to do the cleaning! Oh yeh, you have to
use IE! Also, it is only free until 4/30.
if you did the quick scan, then it must have been quick. but i did the full scan which sucked. it took about 2 hours to scan, a few mins to remove the registry entries, and then 3 or 4 hours to defrag. and at the end, it got stuck at 95%. i do not recommend it.
I personally would avoid it's registry cleaning portion. I skimmed through it to see what it was listing and noticed allot of valid entries marked for removal, needless to say I wasn't going to check some 600 plus displayed entries for verification especially after many of them were incorrectly listed.
Seeing that their registry cleaner looked a bit on the dangerous side I completely removed MS Windows Live Safety Center from my system because I didn't one day want to use it for the virus scanning portion and in not paying attention allow it's registry cleaner to wreak havoc upon my system.