Program Crashes! Please Help!

Hi guys! I have been a big fan of all your wonderful posts and I must say I learned a lot from checking this forum on and off and pardon me if I just leech out info but never have contributed but once I learn a few tricks, I will definitely share as well. I am fairly new using Sketchup and Vray, only 10 months but have been successful in most small sized renderings that are generally 100mb and below.

Please allow me to give you more info on what I use: DELL Precision T1500 Desktop Intel (R) Core (TM) i7 CPU 860 @2.80GHZ 1.17GHZ, 2.96 GB of RAM, and/or MacBook Pro 15" Intel (R) Core (TM) i5 CPU m520 ,2.40ghz, 8gb RAM. Sketchup 6 for modelling and Vray 1.0 for rendering.

My main problem is, I have basically modeled a 1064sqm house with a really huge lawn, the total size of the model as of now is already 120mb and just have 3 units of clip-mapped trees. I normally render using provided .visopts, particularly the gi_irmap_high.visopt. Once I start pressing the render button, initially it will start rendering but after a few minutes, there is a bug splat that comes out , or if not , there will be a prompt bar that says I don't have enough memory in my Temp folder, or the typical " The instruction at "0x01282e9d" referenced memory at "0x00133000". The memory could not be "read" "

I'm not sure how you guys do it, but I assume this kind of project is not so big compared to huge development projects, etc. It is just basically one big house and I can't come up with a nice landscaped output.

If you guys have any idea on what the problem is, please do let me know. My main speculation is the size of the file, that's the main reason why I bought a semi-high powered Macbook Pro but it seems that i'm missing out on something here. Please help

Cheers,
LM