Audi S4 B6 or B7?? Sat-Nav??

[Philgreg]

Ok now you guys will no doubt think me a bit of a numpty for not knowing the difference but up until Wednesday I was driving an X5. I have subsequently chopped it in for a 55 plate S4 Saloon. I have a little knowledge of Audi's having owned four including my wifes current 06 plate TT Quattro Sport. History includes 2 A4's and an A6 Avant.
Well onto the S4. I am unsure whether my September 2005 model is a B6 or B7. What is the difference? My other issue is that the previous owner did not opt for the Sat-Nav and I am considering purchasing one for a retro-fit from an online breaker of all things VW and Audi. My local independant ICE dealer has agreed to install for a reasonable £300 and provide a warranty on the installation. The model number for the unit I am considering is 8H0035192F. Anyone able to give me some advice here?
I'd be grateful for any pointers.

[nickynibbles]

B7 model is the new new current shape, easily distinguishable by the very large grill in the centre of the front of the car that is both above and below the bumper. The B6 grill is a nice wide rectangular grill above the bonnet only, kinda like a big smile rather than a gaping wide mouth!! Being an S4 rather than an RS4 your driving a B6 model, and welcome back to the club! As for the Sat Nav issue, if you really think you need it then fit it! Make sure you ask the breaker for a warranty on the part though, or visit it working if anyway possible. Just having a fitting warranty on the install wont help if it packs in after 1 day!