I think I want a Pegasos but I'm not sure why!

[CLS2086]

Pegasos is like an expended Classic Amiga, without Paula,AGA, and Amiga floppy.
So you won't fell lost, and if you want you can put OS3.9 over MOS 1.4.5 to get the classical felling (and some required files too for some old apps), you can also put OS4emu to get more apps  :lol:

[CLS2086]

At least to enjoy MAME, you'll need 512 mb of RAM (PC2100/ DDR266), but you can use PC3200 too.
For Watching demos and "old" Warp3D games with 15/16 bits mode I suggest you a Voodoo 5-5500 AGP.
For graphics apps and Linux, use a Radeon 9000/9000PRO/8500Le/9100/8500. The 8500 with 128mb is the best (choose a compatible AGP 2x/4x card !!).
You can use "old" Tekram SCSI card (and card that use the same chipsets too).
You can add some more USB2 port (at USB1 speed) with a VIA based card.
You can use any of the TV/FM PCI card supported by GREX.
You can add a sound blaster live! if you really need that.