I recently got a Dell XPS 64-bit Vista for myself. Eclipse doesn't have their 64-bit version, but I've read on forums that they download Eclipse and work with Java 1.5 on the Vista with only some problems. I have Java 1.6 and Netbeans was easily downloadable.
What's the basic/big difference that I'll notice if I shift to Netbeans from Eclipse now?
Maybe when you work with several (many) projects at the same time I would prefer Eclipse (Workspace organization is great for that). Interface seems to respond better (at least vs old versions of NetBeans such as 5.0) in Eclipse too. This is related to SWT vs Swing performance issues, though the differences are no so big as on Java 1.4 days.
However I would say Netbeans is a better integrated IDE, you launch/debug applications the same way no matter you are developing a desktop application or a JSP/Servlet web application. Building relies entirely (since version 4 I think) on Ant, and Netbeans launches/adds ant target transparently. Ant in Eclipse has the same level of integration as a pair of bull horns sticked to the front of your car.
Eclipse is more extensible than Netbeans but the last is more uniform.
The basic workflow of Netbeans is much smoother and more reliable; little things like ^X to cut current line work properly. It's also simple enough to understand what it's doing.
otoh, Eclipse has the emacs quality of being a platform in its own right; some people swear by that.
Edit: I've changed my mind, on coming across HyperAssist: https://bugs.eclipse.org/bugs/show_bug.cgi?id=159157
Quite simply, the HyperAssist plugin fills in the missing piece that kept Eclipse from the gold medal; with it, Eclipse is the best IDE I've ever used.