trojan horse virus

One day I was playing around with WIndows Media Player and a window popped up and said there was some kind of download for wmp and i excepted (didnt fully read it because it said wmp) i clicked accept or ok anyways it came up twice, i ended up restarting the computer because it was acting strange. well my antivirus has been permanently disabled so i download avg pro trial edition, a few days after downloading it i run a scan and 9 issues came up and they all said trojan horse something or another in the line of problems listed.........l i noticed my firewall is off every time my computer is restarted icons are being moved around on my desk top that i didnt move , loss of internet connection among a few other things....my isp said i cant download the security suite from them and expect it to remove the virus i already have, that i have to remove this virus before downloading their mcafee security suite. so im here hoping that someone can help me please. im not that computer literate so please bare with me i have windows xp pro

 

MY COMPUTER IS BEING TAKEN DOWN VERY QUICKLY, CAN SOMEBODY PLEASE HELP ME, I RAN ANOTHER SCAN LAST NIGHT WHEN I WENT TO BED (i disconnected the ethernet cord just bc) and I had 45 INFECTED FILES TODAY, ALL SYSTEM FILES CAN SOMEBODY PLEASE HELP ME THANKS
OH YEAH IM LUCKY I FOUND THIS SITE AGAIN BECAUSE I CANT SAVE THIS SITE TO MY FAVS.

 

Anybody have an idea here?

 

I guess i will definitly not be receiving help from this site go figure!