I always though SLI means Scan Line Interleaving as in one line by one card, next line by the other. But i might be wrong there.
Dual graphic chips for one picture is nothing i want, not on one card and not on two. In my opinion its a pure sales strategy, one high end card is better than two mid end cards and one high end card is enough for everyone who only needs current games. If you do 3D modeling or game design of next years goodies there might be the need for a better card but for private use there is not.
Now the upgrade argument doesnt count either, since when you buy an upgrade in 1 year a better graphic card generation will be out and you want the better generation for more features & better performance at similar power rating, not slightly better performance for double power usage.
When you need more graphic power in a year or two throw away the current card and buy a new one, will fit in the same slot as the previous.
Not all sockel that physicaly fit a conroe are compatible. So you must check if the motherboard can take it. Also if the motherboard can take it with the newest bios revision make sure your board has that revision because you can not update the bios without cpu and you cant use the conroe for updating then.
Serial ATA is diffrent as it transfers the bits one after each other and not 16 at the same time like the old ide ATA. But it transfers them much faster so in the end the data rate is better. You can not use SATA drives on an old IDE interface and vice versa, so if you want to use your old harddrive or more than 2 CD/DVD drives you need a motherboard with at least 2 IDE interfaces which is no longer common.
If you buy a new harddrive you should buy SATA and also have that on your board.... which is on any new motherboard now anyway.
PS why is there no spell check option?