be careful! if its anything like my 2006 jetta you may run into some problems.
first of all (and these are based on my 2006), the front door speaker screwhole diameter sizes are 8" woofer, (i think) 3 1/2 mid range and the tweeter in the sail panel. the speaker size in the woofer location is 6 1/2 but the casing around the speaker fills in the rest.
you'll have to drill out the rivets in the woofer location to get them out. not terribly difficult, but it is a little time consuming.
now, if you have a monsoon system you may run into some trouble. the monsoon speakers are 2 ohm, whereas most aftermarket speakers are 4 ohm. so there will be some loss of power if you have 4 ohm aftermarkets with the monsoon amp.
as much as i love crutchfield, they were not much help with the jetta. last time i checked they only recommend replacing the 3 1/2 mid range (thats the only sing they say will fit...). its a little difficult to find 3 way components in general, though.
if you want to just use a single coaxial 2-way speaker in the woofer location, you'll have to re-wire the system to bypass the stock crossover. audio specialist quoted me about $150 to do this, though your mileage may vary on that.
i'm certainly not an expert and my experiences replacing the front stocks for my 2006 have been somewhat of a nightmare - not sure why VW made this setup so complicated.