Need to get rid of virus, what should I do?

I have a windll virus - and gods know what else on my other computer. It was my sister's and she got a new one, giving this to me. (used it in college to download tons of stuff)

What is the best FREE anti virus? Are there any free anti virus programs that do a good job?

I have a PC. If I must step up and buy protection, which is the best? Norton kept crashing my computer %26gt;=(

I'm also contemplating taking the computer somewhere to get the hard drive wiped clean and re-installing everything. How much should this cost?

Need to get rid of virus, what should I do?systemworks

If you want a free anti-virus I recommend in order of popularity, but please choose the right one for you (install only one):

1. AVG Free

a. A simple interface (easier to use than Avast! and Avira)

b. Can detect about 82.82% of viruses

Cons: low virus detection

2. Avast!

a. Real-time protection

b. It has an option to delete a virus once found

c. Can detect about 87.46% of viruses.

Cons: Too many icons and confusing user interface

3. Avira AntiVir

a. It can detect malware better than Avast and AVG

b. It's cute umbrella icon

c. Can detect about 94.26% of viruses

Cons: A very sluggish update

I advise against Norton anti-virus, it's bloated software that slows your computer down. The best anti-virus available is Kaspersky or NOD32 (recent tests at av-comparatives.org).