SNAPSNET, gadcom.exe, scrscc.exe and username.MR-595BBEC794C4

Hello geeeks!
I'm a damsel in distress who desperately need yr help.
Last night my computer got infected with a virus, a trojan of some description.
Norton pinged up a little square and said it had protected me but oh no! Norton doesn't find anything if I do a scan either... (yes, I know Norton is rubbish, the only reason I have it is because the guy who installed it said it was fine even tho I said it wasn't great and I didn’t really like it just cos he had to show off his male expertise cos it'd hurt his male pride too much that a girl with very limited tech knowledge could possibly know more than him.
But that's beside the point. Let's get back to the point--->)
I've researched the matter as best I’ve could and in task manager, just after starting up when no programs I've manually opened are running and I’m not connected to the internet, I found a few files I’m almost certain are malware:

gadcom.exe
csrssc.exe (no I haven't misspelled csrss.exe)
and I quickly stopped
dPI191065.exe yesterday which seems to have it's origins in the
SNAPSNET folder which from what I’ve gathered is the core of all this...

I've also got double
ccSvcHst.exe
and
ati2evxx.exe (which I believe is something to do with the graphics card. one's on SYSTEM the other myusername.)

2 mysterious files called
McciCMService.exe
and
McciTrayApp.exe
are also there. All the info I can find on them is that they're related to some company called Motive. I don't know what they do so I don't know if they're part of some program I’ve deliberately installed.

Now, my problem is:
All the research I’ve done just says I need to run this, that & the other malware program to properly get rid of the virus. But I don't dare to download ANYTHING now and they all just want me to use their program (which for all I know might be just another virus worse than the first.)

SO THE ACTUAL QUESTIONS HERE ARE:
DO I NEED A PROGRAM or can I find & exterminate this myself (with a bit of help...)?

If not, WHAT PROGRAM DO YOU SUGGEST I USE?

Is there anything i should do BEFORE running the program? Like quitting the suspected processes?
and

WHAT ANTIVIRUS/FIREWALL PROGRAM DO YOU THINK IS THE BEST? (Norton’s going, it's rubbish.)

Also, is it impossible for me to safely back up my pictures and music to an external hard drive?
I've been told the virus can jump into and infect the external hard drive to even if I just copy pictures & music file by file, but I’m not sure I believe it cos I know he doesn't really know that much more than me, so I thought I’d ask someone who do.

I know I’m a girl and I generally shout for male assistance when the blue screen of death appears, figuratively speaking (so glad those days/nights are gone...) but I’ve at least tried to find out how to fix it. It's just that there's too much information and impossible to know who to listen to, but I’ve always found help here before, without even having to register and bother you myself so I thought now that I have a serious problem where else would I go? I'm sorry if my questions are stupid and have already been answered elswhere but I haven't been able to find where and my eyes feels like squares cos I've been staring at the screen too long.
Help me major geeks! Yr my only hope!

I realise I’ve asked about a million questions and written half a novel but I hope you can help even with just a bit of it.

*hug* (There! Now I’ve virtually hugged a geek today!)

//Agitha

Ps:
Another highly peculiar thing that seem to have occured at the same time as reinstalling Windows is that I have two folders with my username on them. One that's just username (only 650mb or so, strangely small anyway, but still containing all the folders & things it should) and one that's
username.MR-595BBEC794C4 (over 6 GB, containing all the same folders as just username except favorites.)
I haven't been able to find any info on this and it doesn't seem to do anything bad, it's just weird. Ever heard of it?

 

Thank you thank you!

Only question now is, do i dare to go on the internet to download it with the infected computer? Can i quit the suspected processes before so it doesn't get worse while i'm online?

Thank you so much for running this site! It's wicked! And thanks for the quick reply!