Will "S" wheels go straight onto a 2.7 with no probs?

[sinly]

I have a 2001 2.7 with 18" gt3 wheels on , however have seen some decent condition S wheels which would be ideal for winter use (use the car everyday). I'm a bit confused aboutthe whole offset thing, and it does say in the manual that the S wheels have a slightly different offset - is this an issue.

Any advise greatly appreciated...btw he's wanting £400 for the set with borderline tread on the rears...would you look elsewhere?