The FIX shouldn’t have returned it to its previous state it effectively clears the infected MBR and sets it to a clean default. So you could effectively run the same risk in using TDSSKiller when you reboot, but honestly you have little choice.

Some times the TDSSKiller can’t get rid of TDL4 MBR Rootkit, but the second aswMBR appears to be clean.

I’m not familiar with the OTS log so I can’t help with that. This TDL4 MBR Rootkit is normally associated with trying to connect with malicious sites (usually using svchost.exe), avast’s Network Shield is very effective at preventing that happening and stopping it download more malware. Unfortunately as you say you haven’t got avast.

A good firewall should also be able to prevent unauthorised outbound connections. Generally the only connection svchost would be making is for windows update.

Unfortunately going back to factory settings can leave you vulnerable in that you will be short on security updates and have an out of date trial version of mcafee, etc.

You would honestly be better off using drive imaging software, that makes an exact image of your system (I do a weekly image backup) and had to use it very recently (completely lost my mouse driver and software) and it took 15 minutes to get back to my last weeks image.

That way you could have avast on there and should you need to restore an image for whatever reason, the maximum you would lose is 6 days of program installations, updates, emails, data files, etc. But with a backup strategy you can avoid lose there also.

Windows 7 does have its own backup function and shadow volume, etc. but I’m not very familiar with that, but it is an other option to avoid going back to factory setup.