as previously said, i would recommend Ubuntu. i use it myself for work, it's stable, secure, looks good, and compiz realy makes work easier with multiple desktops, expo and scale functions which let you easiely find the program you are looking for....
now for the software
Text editors: there really are a lot of them, i personally use krusaders internal editor, because it lets me edit files on the network and saving them directly, without dowloading, saving and the manualy uploading them back (krusader is totalcommander for linux). the editor colors your code (forgot the expression), it supports practicly every language. i love the way you can navigate to a file on a remote server in krusader, press F4, the editor opens, after you're done, just pres ctrl+s and F5 in your browser, and that's it
photoshop gimp is all you'll ever need for editing images, inkscape for vector graphics
antivirus don't and never will need one, the reason is that practically everything on linux is opensource, so what's the point in writing viruses if everyone can see the code and has the ability to discover and delete them. (dont get me wrong, there still are known cases of viruses on linux, about 40 per year, as oposing to windows which has about 40 000 per year)
norton ghost never used it, so cant really help u with that.
i would like to say another thing that i think is important for webdesigners, besides other not so well known browsers (like konqueror) there are firefox and opera for linux, i hear even an IE version is out somwhere (personally i hate IE :P )
to sum it up, i think ubuntu is the perfect solutiuon for webdesign, the only thing it lacks is adobe flash (don't know if that's the official title of the program used for crating flash stuff)
