Ordering custom macbook pro... however

Hi guys, newbie here
decided its time to upgrade my laptop, and whilst my first choice was just a simple upgrade to an ibook 12" ive been captivated by the intel chip.
ive decided to go whole hog and buy the 1.83,
but before ordering it, i noticed the creuddy 5400 spec hdd, so in looking at getting the 7200, ive decided to go that way for a lil more speed.

i did however notice the price drop if i switch to 2x512mbs ram sticks over the conventional 1, 1GB. now i know the limit will be my ram slots are filled. however would there be a performance loss? negligable or viable in making my hdd upgrade pointless to save the cost of that upgrade.

so what u guys think?
btw sorry if doubled some letters, still getting used to new pro keyboard on my mac mini

depends what are you going to use the computer for? if your going to use it as a desktop replacement than get the 7,200rpm drive but if you want to use it out on the road get the 5,400 rpm drive since the battery will last longer with the 5,400 rpm drive.

There is no performance loss when getting 2 512s rather than 1 1GB. In fact, some computers actually make better use of RAM when it's evenly distributed among the slots.

What I would like, is the ability to increase the graphics card on the 1.67. Lame that you can't