Hi Gromered - bummer!
I can offer a few hints as I have picked up a few things since getting 2 'drive-by downloads' in two weeks, when using Brute Force SEO. (I don't blame the software, rather the IE vulnerabilities.)
Anyway, first of all Spybot Search and Destroy. To run as administrator you have to go to the start button, view all programs, find the program, right click and select 'run as administrator' from the right click menu. A bit weird - but that's what you have to do. Now you should be cool with that.
Malwarebytes: this can work, but as others have pointed out you may need to start your computer in safe mode as the malware might stop Malwarebytes from running.
For me, system restore worked for one of my malware issues: but failed the second one and I ended up reinstalling Windows.
Having learned from the experience: I've changed from McAffee to Zone Alarm, as I think it is less targeted by hackers. I started using Spybot Search and Destroy. Using this, I inoculated my browsers. Also, you should set it to auto-update, for which it needs your Windows login (can't do it if you auto-logon, as it uses Windows Scheduler which does not allow that.)
Finally, I have just started using a Firefox add-on called Noscript. it does mean a few extras clicks when you actually do want a script to run, but it does obviously block others which may have bad intent, so I think it's worth it. Having just had two viruses by simply visiting a website, you just had to do everything you can.
I now run BF SEO on a dedicated computer - fortunately I had an old one lying around. It takes 6-7 hours for a typical run, so it needs its own machine anyway, really. For me, anyway. I feel much safer.
Good luck with your virus, and hope this info helps.