Yes, FF 1.5 is the newest version. It hosts new abilities over tabs (you can reorder them with your mouse), an even faster rendering engine (read "gecko updated to better integrate with existing code and the cache is even more efficient". This means folks like me on dialup can pretend we're on broadband when in FF (after the cache fully picks up the page of course, and provided the page isn't fully dynamic)), several security patches, as well as some spiffy new things that I haven't read about (but people alluded to in FF 1.5 review pages).
It is a nice version of FF and soon I shall get the 5 mb file. Does anyone know why its taking FF's integrated update system so long to find the file? I know my update system is working because it just updated one of my extensions. Perhaps FF 1.5 isn't going to be in the IUS (although other releases were...).
If you need more help, PM me and I can point out places to go and whatnot (or just go to firefox.com and it'll link you directly to the MozDev Firefox page, complete with FAQ and forum).
"Don't go there. It's ugly, and it never stops being ugly."
"Naps are good" - Visual C++.NET for Dummies, page 1