Any site you're visiting can tell what your IP address is Banger, whether you're just visiting (not actually logged in) or if you're fully logged in under your user name. (it has to, or it wouldn't know it was 'talking' to your PC)
A site cannot see your IP address unless you go to it though, however there are ways people can find it if they look for you, as long as the PC is connected to t'internet.
People on Broadband are particularly at risk, because they tend to be permanently logged into their ISP.....Broadband providers have ranges of numbers, and because of this, people or programmes 'looking' for 'on' computers will often focus on these ranges specifically.
It's not as bad as it sounds though....as long as you have a firewall, it should stop anyone 'getting in' , and if you're running Anti virus software, you shouldn't be at risk of programmes that contain code that would otherwise make your own computer tell the baddies where it is (ie giving away its IP address)
On top of that, there's a limited amount that 'they' can do with just an IP address.....particularly if you're on Broadband, the chances are all someone will be able to do it track you to the Internet provider and a rough area...for example, all mine gives away is that I'm with NTL and it's based in their Bromley area (I'm actually in Dartford)
Just make sure you're running a firewall (if you're not, go
HERE
and get the free version of Zone Alarm and install it right away.......and if you're not running anti virus software, get some right away as well

(
THIS ONE is free and very good.)
The above is rather over-simplified, but hopefully it makes sense.....
The reality is, as long as you're sensible, you're pretty safe.......and there are enough unprotected PC's out there that if you have a firewall and it's set up properly, they'll piss off and go after an easier target
Just as a matter of interest, what where these 'security issues' ??
