I have a 2011 BTO 27" iMac with the quad-core 3.4GHz Core i7 and the 2GB AMD Radeon HD 6970M myself and transferred all of my data from a G4 as well. No issues what so ever in the transfer itself. Transferring raw data from PPC to Intel is a non-issue because a Mac is a Mac.
Just use Migration Assistant, a FireWire 800 to 400 (9-pin to 6-pin) cable, start up the source Mac while hitting "T", and follow the on-screen prompts and you'll be fine.
When you go the Migration Assistant route, just be sure to transfer only your raw data (user profiles and anything related to it) and skip everything else, including applications; you'll probably need to get updated and Intel-specific applications anyway at this point.
And as previously mentioned, you could go the USB flash drive route but you will probably only get to transfer smaller files (iCal and Address Book exports, Safari Bookmarks, and what ever is in your Documents folder for example). Other things like your iPhoto or iTunes library, assuming you want to keep those intact, will be better handled with Migration Assistant.