The pics listed above are not default.
This is a default AmigaOS 3.5 screenshot.
More screenshots can be seen
here.
AGA is able to do 8-bit (256 colors) in normal display mode and 262144 colors in Hold-And-Modify (HAM) mode (18-bit color, 6-bit per RGB channel). Palette for AGA chipset is 16777216 colors (24-bit). The original Amiga chipset (OCS) had 4096 colors (12-bit, 4-bit per RGB channel), of which 32 could be displayed unless in half-bright (which provided an additional 32 colors fixed at half the brightness of the first 32) or HAM mode. Other features added to AGA over ECS were superhires smooth scrolling and 32-bit memory fetches to supply the graphics data bandwidth for 8 bitplane graphics modes.
However, with a PCI graphics card such as a Voodoo3, etc, OCS/ECS/AGA
games and apps won't be viewable/playable! You could hack a tv card to show the amiga video. The quality sucks though, and it's not very trivial to hack it. <-- Thanks to Piru for this bit of info.
Overall the whole point of owning a PCI graphics card is to obtain higher res, and color depths, at the sacrifice of losing alot of classic games, tech demos, etc.
However not all is lost, you can connect 2 monitors; connect one to the scan doubler for viewing OCS/ECS/AGA games, apps, and tech demos, and connect the other monitor to a graphics card.