Canadian eh? That throws a whole new winky wrinkle into it....

First triple channel memory vs dual channel vs single channel...
With single channel if you have a single 2GB memory chip and that's all you want to put in your system...it will work no problems...ou can put more in 1 stick at a time.
With dual channel, you will need 2 exactly the same specs no variation (unless you want some strange things happening)...if you upgrade it has to be in pairs.
With triple channel...it's 3 times the headache...although the maximum memory for an i7 board is 12GB and the latest LGA 775 board is 8GB.
As far as performance goes..well yeah...you're gonna end up being able to handle more memory, but as of right now the latest LGA 775 motherboard will handle the exact same speed of RAM that i7 boards will take.
The current chipsets that support triple channel aren't faster throughput...it's still in the bleeding edge stages...(my co worker tried to put together an i7 920 based system last month and ended up having to return everything but the PSU because it wouldn't work, so he bought the processor I linked for you and put a system together based on that, and saved a couple of hundred)...
The difference in CPU front side bus speeds is negligible between the i7 2.66GHz and the Core2 Quad 3.0GHz...with the right components...from what I've been able to find on the i7 mobos, the front side is getting choked...whereas the socket 775 mobos are matched...I believe the difference is in the southbridge architecture.
This would be the motherboard for that processor, holds up to 8GB DDR3 memory:
http://www.newegg.com/Product/Product.aspx?Item=N82E16813141009Amazing how many boards out there only support DDR2 instead of DDR3 memory.
As for SLI and Crossfire - you can link 2 cards together (assuming your PSU and mobo support it) and combine the resources for better performance...strangely enough, it's just getting to the point where the driver/software control programs actually support the technology even though it's been out a couple of years...few applications or games actually support it though (can cause weird video problems)...
If that video card is not available for shipping to Canada see what you can find on one of these lists:
http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&N=2010380048%2050001402%201069633099%20106792634&name=GeForce%20GTX%20200%20Serieshttp://www.newegg.com/Product/ProductList.aspx?Submit=ENE&N=2010380048%2050001669%201069633099%20106792634&name=GeForce%20GTX%20200%20SeriesAsk the HTC crew what they use for their 3D modelling...I've seen people still using P4 extreme cpu's.
Forgot to mention...hard drives...whatever you do, use 2...operating system and programs on one...important data on the other...that way if you get an os crash all that stuff you wanted to keep doesn't end up needing a data recovery expert to find it.