For virus, I like AVG – free for personal use. http://www.grisoft.com
Updates quickly upon booting, doesn’t hog resources and catches ‘baddies’.
For spyware, you should run more than one.
I like Spybot - Search & Destroy best. http://www.spybot.info/en/index.html
In the advanced mode, it does a lot more than just spyware. You can ‘innoculate’ your computer against ‘baddies’, delete cookies you don’t want while keeping those you need, etc.
AVG and avast are great, though they are not 100% secure, so take ur chance, but i'd recommend windows live onecare (20.00-50.00 usd/year). If ur convinced with it being free, go avast (or avg), though avast has a friendlier interface.
Avast, I've never gone wrong with this and I have recommended it to a lot of people who have never come back to me and complained.
If you like it you can always upgrade and pay a small fee if you are worried about it not being so secure because its free.