I don't have a vista machine, but it seems to work with 7, so I'd assume so. 
Their registry defrag doesn't seem to be good under 7,
The home page is
http://www.iobit.com/
I use
http://www.savemybutt.com for two reasons,
1. I trust Mike deMichael,
2.  The newer advanced system care is a one click operation, that doesn't 
seem to let me know what it is doing, and then exactly what it did.
I check all the options, in advanced windows care, and run it once a week. 
The first time you run it, it might fix hundreds of registry errors.
I also use ccleaner, which seems to do similar stuff to me, but the 
combination is quite effective.  Then I run spybot search and destroy, but 
only occasionally because it's a bigger project.  Mike has a very good 
computer maintenance tutorial on save my butt, but I modify his instructions 
to accommodate screen reader access concerns.