If you are looking for AV and Spam protection suggestions I would currently recommend Zone Alarm Internet Security v7.
I used to use ZA until a few years back when I found it got a bit flakey (possibly just one version but it was enough to put me off at the time).
Norton was ok until around 2001, after which it seemed to turn into bloatware.
I've currently got F-Secure on an XP box and Kaspersky on Vista. F-Secure in particular is quite "noisy" to start with - discreet windows are not something it's known for

I wouldn't let a bad experience a few years ago put you off. This is a whole new beast and works very well indeed, in my opinion.
I just noticed that ZA Internet Security v7 is the PC PRO magazine A-List choice currently.
Strangely Norton 360 is their second choice! I am used to reading everyone saying Norton AV in particular was known for being a slow, memory hogging hulk, that was only mid-table for detection rates! So presumably they have done a lot of work on it for this new version. They always had a good interface and excellently silent Firewall though.
PC PRO says of Norton 360: "It's Vista compatible, comes with licences for three PCs as standard, and offers a huge range of silent and effective security and system utilities."
I didn't think I would be recommending Norton to anyone, but it looks like I might need to rethink that... silent security is often the best for beginners (as long as it works) as there are less questions to get wrong (thereby potentially compromising the security!). I will be giving it a trial run to see if it solves a clients current problems!
I will take a look...
When I last checked F-Secure a year ago, I found it to be unintuitive, noisy, clunky and a little frustrating, yet the previous version had served me well for a year, and appeared to have excellent security track record! I haven't seen it this year for comparison...
I guess a lot of it is personal preference. Also it shows you need to buy based on this years product, as some products improve and some get worse with each version change. Past record is probably not a very reliable judge (although you want to take it into account)!
Apologies to the original poster, as your question about email providers as been hijacked by a discussion on AV protection.
Mike