i know you can't afford it right now. but i say save for a pegII with MorphOS. it's the ultimate next-generation Amiga experience. even more so than AOS4, which is verging more away from the original transparent/open Commodore OS design we all love.
you can even directly install your old Workbench disks and run that instead of MOS if you like. But MOS is just like a pumpedup version of AmigaDOS/Workbench on steroids, so I doubt you'd do that but the options there. :-D
