Thanks again for your reply.
I tried downloading and installing WST or WTP from Eclipse.org, but unfortunately, it complained that it need EMF. when installing EMF, it complained that it needs RAP. I think It is just getting too much work to keep up with each component's dependencies. Shouldn't all the component already be in the Eclipse SDK distribution?
anyway, I think that installing everything except the SWT Designer XWT support and WindowBuilder Core for XML would work - BUT - what feature will I'll lack (specifically - WindowBuilder Core for XML)