I am ready to buy a GPS unit for my CarPC. What do you guys recomend for a unit that has traffic?

Do I buy the antena and software seperatly? how do I know they are compatable? or do they have kits ? Which ones will integrate WITH live traffic updates ?

I have Sirius, are there any programs that can link with sirius to display traffic in realtime (like the new pioneer and alpine nav units do)

how else would the GPS update traffic? ( would think FM brodcasts would be bogus? or do they work well?)