well the 360 will be running a software Emulator of the xbox1 - So we could get improvements?? Bleemcast on the Dreamcast was a awesome PS1 Emulator for the Dreamcast that doubled the res, cleaned up the graphics and sorted out all the texture tearing etc. So it can be done.
i was extremely disappointed with the ps1 emulation on ps2. Especially since the superb bleemcast and PC emulators out there did a better job. I only play my ps1 games (all originals) on pc (via epsxe emulator) as the graphics look xcellent. The crazy thing is the ps2 has enough grunt to spruce up ps1 graphics.
Now i doubt 360 will do much to improve the look of xbox games tho we uk user may at least be able to see the games in a higher resolution now.
As someone said above I think all Xbox games will have 4x anti-aliasing to smooth out the jaggies but I doubt they'll run at resolutions any different from what they do now so Halo will still only be 480p and Amped 2 will still run in 720p.
The framerates will be the same too perhaps will less evident slowdown where it exists on the Xbox.
Loading times will likely be faster thanks to a 12X over 5X DVD drive. Does that mean that Halo 2's infamous texture draw in problem during cutscenes will be "fixed" on Xbox 360? I hope so...