I live in the states and play an imported copy of WE7 with the combination of Magic Swap discs and a fliptop lid.
PES3 will be slightly improved from WE7 from what I hear, but I'd suggest you think about either: a) importing WE7 or b) waiting till PES3 is released in the US in February 2004 as WE7I.
If you import PES3 from Europe, it's much more difficult to play the game, since you have to get around the PAL-NTSC conversion somehow. The Japanese version of WE7 is already formatted NTSC, so you don't have to worry about that. Also, WE7 is on CD-Rom so it's much easier to patch.
PES3 will be on DVD. For that matter, so will WE7I. I've heard rumours that some folks will try to develop patches for those games, but there's nothing solid at this point. And, unless you have a DVD burner, that won't be possible anyway.