Quarantined generally means that any infected files that could not be fixed/dis-infected have been moved to your quarantine area. Basically these files become non-functional and are cut off from the rest of your system, just like a quarantine in real life. You can leave them or delete the quarantined files, but they aren't really a danger unless you manually try to restore and activate them
If an AV program disinfects a particular virus, that virus is no longer any concern to you, and wouldn't be transferred anywhere else. The only time this is a concern is when the virus is not detected by the software or cannot be fixed.. this is why it is important to keep your virus DB up to date
This is also one of the reasons I prefer to use Linux these days.. all the virus makers are targeted at Windows and it gets tiresome having to keep up with blocking all that shit