Microsoft have released a public beta of IE7. You need to have XP Pro SP2 installed and be fully patched (or at least as fully as MS have patched it anyway!) on your current IE install.
I had a quick try at work today and it looks alright. They've obviously took a lot of inspiration from FF but that's no bad thing. I don't know how secure it is compared to current versions but it still runs ActiveX so many would say not very secure at all.
It's got some sort of anti phishing tool which basically calls back to MS who presumably have a big database of scam sites to check it against. Eeks - MS having a history of your browsing doesn't sound very appealing.
The neatest thing I saw in it was a preview page of all your tabs - it has a thumbnail of each website you have open which is a nice quick way of navigating between tabs.
It's worth a peek - but be careful where you visit while using it. If there are any exploitable holes you can bet there'll be people writing exploits for it right now.