i think the PSP is the best, for 2 reasons
first, USB transfer, which beats out the Dreamcast's CD-Rs.. and i have no clue about the GPs, see next point ^^;
second, and i think, very important, is that it's a current system, currently in worldwide distribution.. this means ANYONE, regardless if they can't order online or import, can get it.. the Dreamcast needs to be hunted for, the GP's, as far as i know, need to be imported
Bookmarks