Viruses? Can't open internet browsers

[Steph19]

I'm currently writing from my macbook pro. I was using my brother's PC laptop to burn some dvds, and after downloading a program from online, I seem to have acquired some viruses on his laptop....it can't open any internet browser. It's more sluggish than it used to be. There are some random programs installed that weren't there before. While the program was downloading, AVG was alerting me that there were viruses and that it was removing them, but at that point it was too late and finishing up downloading.

After startup, a black window with "taskeng.exe" pops up and then goes away.

I uninstalled the program I downloaded. I've tried to uninstall the programs that weren't there before, but it does nothing and then Programs and Features says to wait until it finishes uninstalling the current program (which there is nothing happening).

AVG scan says there are no threats
Spybot Search & Destroy scan found many threats, removed a bunch, but can't remove some due to it being in memory or something like that...

Windows Vista
Dell Inspiron 1520
Intel Core 2 Duo CPU @ 2.00 GHz Processor
2.00 GB RAM
32-bit operating system

The laptop is at least 6 years old....my brother still wants it, so now here I am trying to fix it.

Please help me fix his laptop?

[Steph19]

P.S. I used to have a PC (last year, for 5 years) so I've had experience working with you guys and removing viruses and fixing other issues. I thank you all very much and hope to be able to fix this issue too.

[Steph19]

Sorry, I just realized this is in the wrong forum. I can't figure out how to delete this thread.

Will post my issue in correct forum. Sorry!