I would say go with the more memory as I don't think the added speed of the ddr5 would make that much of a difference.
Now if it were 1Gb of ddr5 that would be even better.
Also don't expect the best out of a laptop no matter the video chip inside.
Say your laptop comes with a model 1 video chipset based off of a model 1 video card you're not going to get everything the model 1 video card has because of space in the laptop.
Also invest in a laptop cooler as it will help prolong the life of your laptop.

The damn cell editor should've been there to begin with without having to resort to these means.
But thanks for the tips!

Lose the Celeron and get a Core2Duo.
Even the cheapest model will outperform a Celeron any day of the week.

Well I'm running one of Nvidia's most current drivers at the moment 169.21 to be exact and I'm not having any graphics propblems like that.
 I also play F.E.A.R. ,Half-Life 2 and Oblivion without too many issues either.
I'm using two 7800 gtx cards that are right below the 7900 you're using too so it should be ok to use this driver with that card.
One thing I would highly recommend is that you use the Driver Cleaner Pro program to clean out your drivers on your computer BUT make sure you read the readme in there before you use it.
http://downloads.guru3d.com/download.php?det=745