I nominated the wii

Could someone write a list of retro games for the XBox360? Please!!! 

While I am here pushing the Wiis case, I would also like to mention controls. I think the Wiimote and Classic controller are much better suited to 8 bit and 16 bit gaming as they are closer to the original controls these games were designed for.
The 360 controller is great for FPS games and driving games but is not so good for Pac Man as the 360 dpad is poor and the analogue stick is not so good for a quick 4 direction input.

that lots great if you like zelda / mario etc . But again i make a point that playing track n field / doom or another classic game beats the hell out of playing super mario world for the hundreth time .

I do like Nintendo and do have 2 wii machines , 1 black , 1 white , but hardly ever download off the vitrual downloads , i prefer outrun coast 2 coast (online with mates) or afterburner climax etc on 360 , anything i seem to look at getting on the wii , i already have or i can't get anymore use out of it because it might just be a straight port with no new features to endear me to purchase it..

I also have at least 4 gamecubes , with a huge collection of games , i dont need to download any of those either , but i would download mario party 4 , 5 , 6 or 7 if it was available and also available to play online with mates , something which doesn't seem to work for me on the wii.

Each to their own and peace !

Both great machines , but i disagree that the wii's bettter for retro gaming

 You do not need to modify a Wii to install the homebrew channel but it is a fair point. Out of official releases, many of the best games of all time are available on the Wii. In a recent list of best ever games put together by Edge magazine (I know these things can be contentious), 8 of the top 10 games were available on the Wii. The games were:

1) Zelda Ocarina Of Time
2) Super Mario 64
3) Half Life 2 (not on Wii, but is on 360)
4) Resident evil 4
5) Zelda: A Link To The Past
6) Super Mario World
7) tetris (also on 360)
8) Super Mario Galaxy
9) Halo 3 (only on 360)
10 Yoshis Island

Many of the Wiis current releases are practically retro gaming.

As well as all the Wii stuff and virtual arcade, there is also Gamecube compatibility. the GC had many retro collections as well as Metal Gear Solid, the Resident Evil series, and many Dreamcast games ported (including Ikaruga and Sonic Adventure).

I think the Wii is a retro gamers dream and trhe 360 is better for modern jaw dropping stuff.

Im talking about official releases , not dosbox or emulation on the wii . Any machine thats been modified can have the best retro games on it.

I prefer playing track n field etc on the 360 arcade against a mate on xblive , the same goes for doom . Plus i can play against all the lads on retrogame via the live arcade room , set up leaderboards or challenges , far more fun trying to beat someones score who you know .

 As far as I can see Duke Nukem 3D and the original XBox titles are the only retro game available on the 360 that is not available on the Wii. It may be possible to play Duke Nukem 3d using DOS Box on the Wii though.

360 - via the arcade feature and super compilations such as the namco and megadrive discs , also enjoy the live leaderboards , make it feel like a proper bo arcade .

Easily the Wii. As well as Gamecube stuff and Virtual Console, there is also the homebrew channel which will let have emulators for ZX Spectrum, C64, Amstrad, NES, Master system, SNES, Mega Drive, gameboy, PC Engine, GBA, PSOne, N64, and loads more.

I voted the 360 as there are loads of arcade classics on the platform and with the 360 Arcade bringing it all together - it's a pretty awesome machine for retro.