just wanted to let you know that i just added a 4gb ram chip to bring the total to 6gb...no problems at all....no real speed gain to speak of, i am sure it helps when several apps are open though....140$
added a 256gb ocz vertex SSD....i have a new mbp....things are flying.....not only mail, safari and such....most noticeable with aperture and to some extent with CS....processor obviously not faster but anything scratch/disk related just flies....700$
now: the drive in this mbp is limited by the 1.5gbit SATA but definitely makes use of that speed....i am planing to simply transfer this drive to a new one when the quad core mbps come out (soon?)...
looked into the 34 card drives...some issues....they get really hot, speed is not THAT great (especially compared to the vertex) and they are not THAT cheap either...also 10.6 is picky when it comes to the 34 port.....i also use a SATA card in it to speed up external things which is really worth it...almost twice fw800 speed.....
hope that helps....