In addition to what Elspeth said, contact the three credit reporting agencies and your bank and credit card companies and enter fraud alerts. Change all your passwords for online access but ONLY after you have had your computer verified as being free from malware or use another computer you are certain is safe.  The software he loaded may be sending all your logins, passwords, credit card and bank info to him when you are online.  Even your email account(s) may be compromised.

Take your computer to a reputable computer store - you don't know what he downloaded onto it while you gave him access.  They may need to reformat the hard drive (erase everything) to get rid of malware/viruses.  As an FYI - Microsoft nor Microsoft partners call you unless you have called them first.

I received a call from a person named Jason Marsh on Saturday night.  He told me he was a windows support tech and that my computer had a lot of problems and was about to crash.  Being new to the computer I was stupid enough to give him access.  He then tried to get me to pay $50.00 dollars for the program that he downloaded so i told him i would think about it.  Today I just received a call and when i told him i was not going to pay the money and that i have all his information he started swearing at me and telling me that he was going to make a porn movie of me and put it on U TUBE.  I also informed him that i have talked to the police which made him even madder.

Unfair coincidence, he had an indian accent.

We got a call from this number today, telling us it was Windows tech support. They said that our computer had a lot of errors and other malicious "events". Since we didn't have a way to know for sure that this was really a Windows call (unidentified caller, seemed eager to get it over with), we tried to make him give us some information about him. Anyways, he wanted us to grant him access to our computer by using Ammy Admin software, so he could solve the problems, a task that he considered to be extremely urgent. We did NOT grant him this access, because he was unable to proof that he was not a hacker, and finally hung up.

After a little research online, apparently this really is a scam (check out the official warning from the Ammy company: http://www.ammyy.com/en/admin_mu.html). Be careful.

If you have some more information about this situation, please share. This are some of the things we were able to write down:

Caller: Sam Wilson, from Windows tech support
Phone number (he finally agreed to give us): 2012855221