I just received my hitachi travelstar 7k200 today and I have to say that coming from the hitachi travelstar 7k100 its much much faster. The burst speeds is very noticable and boot time is much quicker. I also I love the applications that load quicker and files transfers are a bit faster as well.
But the best thing I love about it compared to the 7k100 is the heat. It never gets hot!!! It feels like I have a 5400 rpm harddrive installed and it never gets hot. At the most I've felt it on the left palm rest just a tad warm. With the 7k100(7200rpm 100gb hitachi) when I played a game in windows vista that was pretty intensive for an hour, my palm rest on the left side would be so hot that my hands start to sweat. But good news now it only gets a tad warm at the most after an hour and a half of intensive gaming!!
One other thing is that when I first installed the drive and installed the osx and installing windows vista, after all that installation the left palm rest used to be very hot and once again very cool =D. I think one of the features that said about the 7k200 is that puts out heat as much as a 5400rpm, like some new technology or something =D.
oh and you can switch out the harddrive and will not void your warranty. Just remember if you ship your macbook pro to apple care just swap back to the original harddrive and rams and everything is good =D have done it since the powerbooks.
Oh and dont worry about installing the harddrive, it only took me 10-15 minutes, very easy. Just 4 screws on the side where the dvi is and 4 screws on the other side where the power plug goes, and 4 screws on the bottom and 2 screws where the back of the hinge is and 3 screws where the battery is and 2 star shaped screws under where the rams are and then just pop the top part off (doesnt even snap off just comes right off very easy compared to the 15" sr mbp that one snaps on a bit scary). Well just lift the top off comes off without any snap or resistance, and just lift it up a bit and just pull the keyboard ribbon out just snaps right out no worries and that's it. The harddrive is just right there on the left side of the palm rest just 2 screws that holds it down with one more ribbon cable. Just replace it, very common sense driven. And swap and put everything back. I just use 2 pieces of papers to draw where the screws exactly go in.