That is somewhat strange as the avast folder should be empty (other than the webshlock.txt file), on completion of any scan that places files in this folder it should also clear the .tmp files.

Avast uses a localhost proxy so that http web traffic can be scanned, so instead of seeing your browser reported in all instances in any logging, they are redirected through the proxy. So avast isn’t actually instigating these connections only redirecting them.

McAfee has an uninstall tool that you could run to ensure any possible remnants are removed. Check out this page for removal tool and instructions, http://service.mcafee.com/FAQDocument.aspx?id=TS100507

Well the avast/antivirus section in the XP Event Viewer should no longer be there. This was as it used to be with avast5 I believe, but was discontinued in avast6, but depending on how avast6 was installed that might remain.

So what version of avast do you have installed, the latest is 6.0.1289 ?