It would be nice if you had specs on it. From the top of my head, The APple probably wouldn't be good for gaming. I know the older ibook's or something had like FX5500's in them as the stock card. The E1505 i believe you can upgrade to a 7900GS? Or a X1400XT which putting it an easy way sucks. Never heard of the Sony SZ.
Here is what i would recommend
Core duo, Intel centrino, AMD 64 - Multitasking, gaming, downloads
At least 1GB of ram, more would be +++
Hdd space, you probably know how much you would need 60GB+
Video card is what you want to mainly focus on gaming, something along sides a 7800 and upwards, I think a 6800 ultra would hold you over to. If it is what you want to play on high settings of these games out right now. 7300, 7400, X1400, X1300, intel integrated. All these graphics card stay away they suck!!
AIM/Xfire - pzerofgh