I wouldn't go for that particular Gateway if you have gaming in mind. It just won't live up to your expectations if you're aiming for any games produced in the last couple years.
The HP linked is overpriced for what you get, and with a native res of 1440x900 on a 17" laptop screen... you're getting kinda ripped off. :X (besides, there's really no point to using blu-ray at that resolution either) If you really want to spend $1400 on a laptop, and are dead set on an Intel core, this is your best bet.
http://www.newegg.com/Product/Product.aspx?Item=N82E16834220379 Excellent native resolution, fast hard drive, solid cpu, good mobile gaming video card. Don't expect it to last too long on battery life if you plan to game without being plugged into the wall, but if you just want to watch a movie or something you should be fine.
If you'd like something a little more compact, less of an impact on the wallet, and still a good performer, check this one out.
http://www.newegg.com/Product/Product.aspx?Item=N82E16834220348 Solid cpu, gaming video card, plenty of memory.
The big thing with the whole 3gb vs 4gb pertains to the operating system. But, its not just that Vista can "see 4gb" where XP "sees 3gb." It has to do with being a 32 or 64 bit operating system. Vista 32 bit will only "see" 3gb, as it assigns the other gb to other hardware. Your computer will still make use of all 4gb, and you would benefit from two identical sticks of ram to make best use of dual channel memory. With Vista 64 bit, the operating system can assign all 4gb to the page file directory. (32 bit has limitations, and basically tops out at 3gb, so it just gives the other gig to stuff like onboard video, sound, etc.) Either way, you'd want to make use of the dual channel memory. (hence, 2 x 1gb sticks instead of a single 2gb stick, etc.)
Whichever way you go, here's basically what you'll want to look for.
- A dual core (2.0ghz+) processor, either from AMD or Intel (I'm not going into the Intel vs AMD debate here... suffice it to say that they're both good choices)
- A 7200rpm hard drive. (5400 is acceptable, but 7200 yields better performance, particularly for gaming when you are accessing random files on the hdd frequently) Volume isn't too important, as basically anything over 160gb (industry standard) will be more than enough. If you have THAT much... errr... "stuff" you have downloaded, an external hard drive to store everything would be a good option, to keep the internal hard drive free for program files.
- 4gb RAM. Kinda touched on this earlier.
- Geforce 9600M/ATI Mobility 3650 or better. A higher number in the 0x00 (x's location) will generally indicate a higher performance level to be expected.
- 1680x1050 native res if the monitor is 17" (or 1920x1200 if you really want to shell out) or 1280x800 native res if the monitor is 15.4"
Good luck to you either way. (and check Newegg frequently, as they have daily deals on stuff... sometimes its just hard drives and cpu's, other times its laptops)