As a computer tech who's spent YEARS dealing with computer that have been hacked into, smithfrauded, virused, etc...
This is my list of suggestions:
1. ALWAYS use a good, reputable internet security suite including firewall and a spam/phishing mail blocker. McAffee Internet Security Suite is my favorite (Stay away from Norton this time around... between the two, McAffee has gotten the better reviews and it handles add/spyware much better.)
2.Along with the security suite, use a spyware, addware blocker/cleaner. Spybot Seach & Destroy is my favorite because it allows you to blacklist every bit of add/spyware in it's database. Be wary.. some idiots out there put out spyware/addware/viruses under the guises of spyware/addware removal programs. I've even seen hacked versions of pretty much every popular add/spyware remover that actually fill your computer with viruses and add/spyware. If you decide to do Spybot Search and Destroy, get it from
www.Download.com.
3. If you do ANYTHING P2P, make sure you scan the file with your virus scanner before you even touch it. (Make sure your virus scanner can open and look inside of archive files... McAffee does).
4.
Keep the above programs updated !!!! Check for updates once a week !!!
5.
Do a FULL SCAN of ALL files in your system including archive files at least once a week. Do this with the virus scanner AND the spy/addware program.
6.
If you have a wireless router, make sure you have a WEP passcode to get in. Do not leave the router open so your neighbor can hop on your connection.
7. Be wary of where you web surf . Use common sense.
Follow the above steps and you should be pretty darn safe.