It is a different case for me in the UK. (I guess you guys are from the US)
I have got an Early-2008 MBP top-spec model with 512MB graphics. The hard drive was damaged with bad sectors three days after I got a new hard drive, so I got offered a replacement MBP.
HOWEVER, they only allows me to get the base model with the lowest spec, their reason being the base model is already better compared to my ex-MBP. I find no way to convince them that the 512mb is way greater than the 330M 256mb. So, they are shipping the base model with 256mb 330M for me.
BUT, I will try to call Applecare and tell them they have not got amy ExpressSlot on the 15", so just *fingers crossed* hope that they are willing to ship the 17" for me, just hope really... If not, I would also want to call them and ask if they could replace the top-end 512mb 330M for me, with luck of course.