Amiga OS 4.1 is a nice system which I personally think is worth getting (I know, because I have it). The SAM440 is on the expensive side, but if you want to play around with a modern Amiga, it's worth it.
Old software should work fine so long as it doesn't bang the hardware directly. For browsing, OWB is a CSS capable browser that will allow you to view most sites on the web (no Flash yet, so Flash based sites won't work). There are some office programs available, particularly via Cygnix (an X11 port). If you need Open-Office/MS-Office, however, you'll have to stick with your PC. Yes, it can read old A1200 hard-drives.
If you want to play with an Amiga again, and want one that has more modern features, I'd say go out and get it. We're continually working on bringing more software to the platform so the mode users/developers that come on board, the better. If you know someone with Amiga OS 4.1, or can make it to one of the shows (e.g., Pianeta Amiga), you'll be able to check it out before buying.
Hans
P.S. yes, a Blender port is in the works, but it's not quite done yet.