I'm on IE 6 using a work computer that has a pretty decent lock down on it. They have McAffee installed for the firewall and antivirus and I can't touch settings on it.

For IE here is where I am:
Tools->Options->Security (all preset by work)
Internet: Medium
Local Intranet: Medium-low
Trusted Sites: low
Restricted Site: High

Tools -> Internet Options->Privacy
Custom -> Advanced: Override auto cookie handling, Accept 1st and 3rd party cookies, always allow session cookies, Allow pop-ups

I never have issues with surveys crediting, shopping is at 70% right now (not sure why) and freebies are 50/50 but I think that's because I've been around for a while and am in most databases and changing emails doesn't help when they track by address or phone numbers.