Last week, Russian hackers may have broken into 6.5 LinkedIn passwords...you can check to see if your were affected > https://lastpass.com/linkedin/
(Note: this is from LastPass, a secure cloud site to safely store passwords. They are rated as a trusted site
If you were affected, your LinkedIn is safe, BUT if you use that same password elsewhere, you could get hacked.
Use a password of eight characters or longer - that's a strong password defined.
Make it phrases you remember easily like a loved one + "June2012" ... something like that.
Change it periodically or when you are concerned.
If you don't full scan overnight at least weekly - you are playing with fire. Many good products, but MSE (Microsoft Security Essentials), AVG, and Avast are free and don't drag your computer down. Malwarebytes is also an excellent product.
Be Very careful checking emails - very careful
Hover and check the email to see if the address is strange and from a country like .ru (many Russian spammers) Also check for stranges names, subjects or no subject.
If you click anyway - is there any content to go with the link? If the verbage does not address you or suggest they actually know you or they are urging you to click the link - DON'T - that's how you get malware.