[Belgium] Would this laptop be as good as my previous one?

Hi everyone!

I'm thinking of buying a new laptop because the PSU of my now 3.5 year old HP Compaq 8510p (Intel Core 2 Duo processor T7300 / 2 GB RAM / 15.4" 1280x800 / ATI Mobility Radeon HD 2600) broke.
The thing is though, this laptop was actually really good and even now it still played new games (eg.
Mass Effect 2) without any trouble.

I bought it at university (requirement to start those studies) for 1200 EUR / around $1600.
I'm not sure if that was the regular price or if they made us a deal because a large amount of students were buying it, though.

Either way, if I buy a new laptop I would prefer one that is as good now as the HP was then (if you know what I mean ).
I'm not too good at judging that however, so I would appreciate some help.

I've been looking around and I found a few laptops I'm interested in.
I'd like to go for Toshiba.
The one I currently have my eye on is fairly expensive but I think it looks good.
I'd love to hear the opinion of some other people though.

Laptop in question: Qosmio X500-14X
Intel Core i7-740QM (2.93GHz)
4GB DDR3 SDRAM
500GB SATA 5400 rpm
18.4" HD+ TruBrite 1680 x 945
NVIDIA GeForce GTS 360M (1GB DDR3)
442.6 x 294.2 x 41.5 mm
4.6 kg

I was wondering, would it be possible to keep this thing on your lap or would it be too large/heavy? Is 4GB RAM enough, considering it's been the standard for quite awhile? And what about the resolution? I like to watch things in HD but sadly it's not a full HD screen.
Would it make a big difference?

Some cheaper alternatives I had in mind were Satellite L670-1DX (Intel Core i5 460M / 4 GB RAM / 17.3" 1600x900) and Satellite L670-17M (Intel Core i5 450M / 6 GB RAM / 17.3" 1600x900).

I'm looking forward to hearing your opinion, so if you can tell me anything that could be of use, please don't hesitate.