While I've never been shy of letting Dammy know when I think he's behaving silly I must admit the shots at him are somewhat unwarranted here. Most of the "corrections", etc. that people are aiming at him here are in response to things he's not even said.
Now as for buying a SAM, if you want a machine to play your old amiga games, etc. as youve said, then perhaps ironically AmigaOS4 + a Sam460 isnt really what youre after. Huge pricetag, poor performance (relative to pretty much anything made within the last 10 years), and too slow for a lot of software. Forget Breathless, AB3d, AB3d2, even Alladin, Capital Punishment, most AGA games wont play full speed. Yes, OS4.x (and MOS) do have 68k emulation outside of UAE, but is that of use to you seeing as you expressed a want to use your old custom chipset based software? In short, it'll be an ok experience, but expect compromises and some of the better amiga games not to work. Chances are you'll get people trying to convince you otherwise while trying to get you onboard, but again, if youre mostly after a machine to use your old favorites a Sam + OS4.x would be one of the last things I suggest. Do you want to spend over a thousand dollars for inferior custom chipset performance to what you'd get off a machine you'd find in the bin? As for people suggesting that the speed of modern computers being redundant for AmigaOS, that's a crock. There's plenty of stuff to take advantage of extra resources, especially with a machine that requires raw speed more than things like Windows,Linux, etc. (cos of modest driver suppot amongst other things). Videos, emulation, compiling, audio transcoding, 3d rendering, etc, etc.... pretty much same sort of software as other formats, only yhe need for speed is greater for Amiga derived OSes (even if the destop/UI/etc. is very fast and responsive on low spec hardware you still need raw grunt for intensive software).
Anyway, despite how it may seem, I actually do like OS4.x, I just wanted to be honest here as a lot of the answers you'll get will be written with an air of bias, and truths twisted because of it.
If use of the OS and/or system friendly software is important to you then the perspective on value is somewhat different, and in that case you might be happy with a Sam+OS4. That said however though then this also may mean one of the alternatives in MOS and AROS might also suit you. The former also having an intergrated 68k emulator (again for non custom chipset software), while the latter offers a custom intergrated version of UAE and much better performance in UAE.
Anyway, I hope this info is of use to you, I just thought Id offer the perspective of someone with no bias or alternate agenda
