Several things noted here. You are running two anti-virus programs on the machine at the same time, McAfee and AVG 8. The absolute rule is ONE anti-virus on a computer. More than one can lessen protection. One of these MUST be UNINSTALLED immediately. You choose. If McAfee is current, not set to expire soon then keep that one since it is a paid program OR if your AVG 8 is the paid version then you will have to choose. But one MUST BE UNINSTALLED before you go further. Note I say UNINSTALLED, NOT DELETED. You must go through the Uninstall Process for which ever program you choose.

You only ran a Quick Scan with MBA-M.
Instructions are very clear:
I would like you to run the program again and allow it to Remove All that is found. Save the log for posting back here along with a NEW HJT log.

Note where the infections WERE found in the original MBA-M scan;
C:\Documents and Settings\computer\Start Menu\Programs\BitDownload P2P File sharing should always be considered dangerous. This is not an activity we encourage here, and now you can see why. Discontinue this for your computer's safety and the safety of the computers of others you may correspond with via email and possibly IM programs.
Do you know what the most recent program you downloaded via BitTorrent might be? It could be an earlier one of course but since the problems began when you installed FireFox then what did you install prior to that or just after that?

Now what shows is a LOP infection. When you go to a web site using an hostname, like www.daniweb.com, instead of an IP address, your computer uses a DNS server to resolve the hostname into an IP address like 192.168.1.0. Domain hacks are when the Hijacker changes the DNS servers on your machine to point to their own server, where they can direct you to any site they want.
Where are you located?

Please answer the above questions and complete the FULL scan with MBA-M and post the log back here.