To SergeDem, congrats on the new purchase. My friend has the HP zd6000 (or whatever the HP equivlent is). Grand Theft Auto is not really that intensive, try changing the resolution to the LCD's native resolution and see if that changes the game performance. Good luck with instaling the second stick of RAM.
To Besttopray, the R4000 is pretty good. I was originally going to get the HP zd6000 but decided that the ATI x200M gpu was not enough for what I wanted. The computer you configured looks pretty good but you could afford to go down to the AMD Athlon 64 3500+. Both the HP and Compaq notebooks use the ATI X200M chipset, this does not support dual channel RAM. With AMD Athlon 64 processors, their memory controller is in the processor. The newer AMD Athlon 64 processors support dual channel RAM (doesn't matter if it is DDR or DDR2). By having a chipset that is not compatible with dual channel ram, it is really hindering the performance of the AMD Athlon 64 processor. So the performance difference between the 3500+ and 4000+ are slight. With the current R4000, a AMD Athlon 64 4000+ performs like an older AMD Athlon 64 3500+.
For the average user this doesn't mean anything as it will still be fast. But for the intensive user who need the ultimate performance, this will tear them away from purchasing the R4000. Of course the intense user won't be purchasing the R4000 as they will probably need a more powerful gpu than the ATI x200M.
The R4000 and zd6000 are fine notebooks. They are desktop replacements so they are kinda heavy but not as heavy as 17 inch notebooks. The battery life is over 2 hours which is pretty darned good for a desktop processor.
As I said earlier. I was going to get the R4000 or zd6000 until my notebook budget drastically increased. Feel good about getting one of those notebooks as the AMD Athlon 64 processors are at the tops of their games.