128 MB or more is recommended, but Windows 2000 Pro by far is the best Windows OS for a laptop, or any recent Windows PC for that matter. 64 is completely unacceptable. Never tried 96, but I'd imagine that's really pushing it. Networking is a snap by the way under Windows 2000, and seems much more secure. This is assuming you have the right drivers, of course, which is more than likely if you have a fairly common machine.
I dual boot 98 and 2000 on my PC (256 MB), both using FAT32, and I run 2000 on my laptop (128 MB for now) exclusively, using NTFS.
Memory is cheap nowadays, at
www.crucial.com, assuming you can still upgrade.