<<...was infected with several trojans and other malware, some stupid toolbars were also installed. I have cleaned it which involved some registry interference and so I'd like to make sure that "things" are back to place...>>
Well...depending on the malware involved, there is no such thing as "cleaning"...some malware call for a clean install. I might also mention that every day...we have users assert that they have "cleaned" infected systems, only to find that the system is still infected. Before I undertook what might be an extensive waste of time...I think that I would initiate a topic at Am I infected What do I do - http://www.bleepingcomputer.com/forums/forum103.html
Using sfc /scannow...will not correct registry entries that are damaged or missing.
Lastly...there are some problems that occur as the result of malware and attempts to neutralize such...that will not be overcome by running sfc /scannow or attempting a repair install. Not all problems with a system...are file problems.
You might read http://www.bleepingcomputer.com/forums/topic43051.html
, as well as other links on this command which are available via Google.
I've found that it's best to have the XP install disk, rather than rely on some of the edits suggested as working to ensure that sfc /scannow performs properly.