SSD drives are really good in laptops almost instant booting and opening of applications MUCH better than a regular HDD. The latest Vaios have 4 x Samsung SSD in a striped RAID configuration and the OS loads faster than the BIOS!!
NEVER buy a macbook with any more than the smallest drive and RAM. Both drives and memory are available, (same or better spec), and it is easy to change yourself + you have the old ones if you need it to go back for a warranty repair or to sell.
The memory IS a user update-able part and there are official Apple instructions to replace it on their website... HDD happens to be accessible when you are doing it:)
http://support.apple.com/kb/ht1270
I have personally done this and saved loads, only thing I recommend is getting some of the sticky stuff they put in the screw holes to ensure the screws stay fixed as within 6 months I had lost a screw from the bottom but for £2 Apple sold me a pack of screws and a tube of the stuff that stops them coming loose.