Laptop Comparison

Hello everyone! I am new to Tom's, but it looks like an awesome forum. Hopefully you all can help me out a bit.

I am currently looking to buy a new computer. My wife and I have been getting by on her 6 year old Gateway (which has crashed multiple time and I have managed to save) and my 4 year old HP (on which things are dying left and right, i.e. the sound, the CD drive, etc.). So it is about time we got a new one. We are something of a budget, however, so I am looking at the $500 range. Or thereabouts.

I have found these two computers which really interest me, but they differ in some major ways.

http://www.staples.ca/ENG/Catalog/cat_sku.asp?CatIds=,&...

http://www.futureshop.ca/en-CA/product/gateway-gateway-...

The thing that has me most caught up is not being 100% sure which processor I like better. The idea of a quad (in the Gateway) really interests me, but at 1.5Ghz, I am just not sure that the quad cores are enough to make me go for it. I mean the 2.5Ghz of the Toshiba is great, which is no surprise seeing as though it is a Gen 3 Intel. I realize that the choice between more lower clocked cores or fewer higher clocked cores depends largely upon what applications you will be using. I myself am something of a gamer. I don't play too many of the brand new games with amazing graphics. Mostly I like MMOs (WoW, LOTRO, etc.). I do hope to play things such as Starcraft 2 and other similar games, though the newest Modern Warfare or others like that which require the very heavy hitting GPUs and CPUs aren't exactly what I am interested in. I also do a lot of work with applications such as Word, Excel, and other data processing tools (Graphpad, ArcGIS, etc.). Often I have many of those things up at once, whilst listening to music or whatnot. My wife on the other hand really only watched TV on the 'net and uses the internet, so her computer interests do not hold much sway on the choice here.

Basically my question is this: would going with the more cores (i.e. the Gateway) have a significant impact on game performance? I like to play games on high settings and high resolution. I know that the four cores will make multitasking when I am working on data processing much faster, but I am willing to let that take a back seat to game performance if the dual would actually be better. There is also the question of the integrated Intel HD GPU vs. the dedicated Radeon HD GPU. I know the Intel HD 4000 has come leaps and bounds since the HD 3000, but can it match the power of the dedicated card?

Finally, what about the brands as a whole. My wife has a Gateway that we are still using 6 years later and it works more or less fine (except being really old). Neither of us have owned Toshibas, so we don't really know what to expect.

Thanks for any insight you have got and sorry about the rambling, I just wanted to throw all the cards on the table. Cheers.