HELP : Avenue A Inc. and MRU List

the Bad Download Blocker and (at very bottom) tick the box for "notify when blocking" you'll know which site it's comming from as well as prevent its' re-install.
To enable Browser Helper bad download block: Click on immunize sheild and look at bottom of page for the check box. Remember to press the green cross at top of same page to double check you're fully immunized (despite box saying "all known bad... already blocked) after each update. This should help.

AvenueA is only a tracking cookie and if you are using IE you can block that by hitting the immunize shield on the left side of the page on Spybot. That will take you to the immunize page. On the bottom, make sure there is a check mark where it says ''enable permanent blocking of bad addresses in Internet Explorer''. In the dropdown box below that, I would choose ''block all bad pages silently'' so you don't get a bunch of popups every time you visit a web page. Then, on the top of the page click the green ''+'' sign which will activate that protection. Remember to do that each time you download updates. The MRU's on Ad-Aware are nothing and most people, including me don't even scan for them. The next time you do a scan, when you click ''start'' at the bottom, the next page where you choose which type of scan to do, you can UNcheck where it says ''search for negligible risks'' and you won't see them anymore. I use CCleaner which is a different program to get rid of those. Regardless, none of the above items will slow the computer down so you have another problem that is causing that. I would also add SpywareBlaster by Javacool as an extra blocking program for both IE and Firefox. It is free and you can get it here.
SpywareBlaster (a blocker only, download it, check for updates, enable it and leave it alone except for checking for updates occasionally)
http://www.javacoolsoftware.com/spywareblaster.html