'05 or earleir Boxster and other questions

[2005Boxster]

Hi all,

I am in the process of researching the purchase of a Boxster. I would be greatful for advice on whether I should go with an 05 Boxster base, an earlier base, or an earlier S. I currently drive an 04 S2000. I love the car but need something I can commute in year round in Wisconsin winters. So I'll need PSM and a set of snow tires. The S2000 has no traction control and is too noisy on a long commute.

I could also use advice on whether I should go with the Bose system. If I do, is it possible to switch speakers if I don't love the sound, or has Bose made them with odd Ohm loads? Also, is it possible to have XM or sirius with the Bose system (05 or earlier)? Can anyone fill me in on speakers that are compatible?

Thanks,

Ken