Hi grrr.
Whether you prefer a paid or free alternative, your choices are great.
Our own Windows 7 SP 1 is protected by ESET NOD 32 & Windows Firewall.
If you'd prefer a suite including an integrated firewall, you can try a 30 day trial of ESET Smart Security.
Just about any paid AV can be tested for 30 days in order for you to find one that fulfills your needs.
If you've currently no AV in place, why not activate the native Microsoft Security Essentials?
Another free choice you might consider is Avast!
There are also some free Holiday Giveaways here. Just look near the top of this page, or go to our Free Giveaways section!
Good luck, and Happy Holidays!