Windows version of AIM runs pretty much perfectly under WINE. Diablo II does too from what I hear, though I've never tried. I successfully got KaZaA working in WINE, along with Winzip 8 and Textpad and my Windows NES emulator and Warcraft II and some other stuff. The hardest part about using WINE is setting it up to begin with I think. After that the hardest part is finding all the libraries you need. http://appdb.winehq.com/appindex.php is very helpful getting things to work. People leave comments of what problems they had and how they fixed them, usually listing specific dlls to download and specific sites to get them from, and if people there say something doesn't work in WINE you can be pretty sure it doesn't. As far as RO goes though, you're out of luck I'm guessing. WINE has a Windows registry, but it's not exactly like a real Windows one of course, because a lot of stuff is hard-coded into the wineserver and bypasses registry stuff I think.

They're coming out with a new version of GAIM soon. Version .60 or something. It's going to support file transfers. Yay. File transfers are all I miss from AIM.