Java and Flash is still a bit ify on x86_64 linux - although this could be worked around with a chroot if required. If you were going the 64-bit route, go for the Dapper beta - having done both Breezy and Dapper AMD64 installs - Dapper was a lot easier going. Although it's in beta (beta 2 or 3 now IIRC), it's been pretty much rock solid from Flight 3.