First off, to anyone who has never played the original Rainbow Six... now you have no excuse.
http://www.amazon.com/gp/product/B0000AFWWE/ref=oh_details_o00_s00_i00
I have tested the first Rainbow Six game, and have confirmed that not only does it work under a modern Windows 7 x64 build, it actually still supports the glorious NATO ARMM mod. Sadly, it does not include Eagle Watch, but from what I've seen, those five missions are not a huge loss.
You will probably want to remap the keys, though, as the movement, go-codes, reload, and more are not in the spots you are used to.
This pack also includes Rogue Spear, which I haven't tested yet, but is one of the best. The only problem is it does not have Urban Operations, which is a damn fine expansion.
There is also another game, but I know nothing about it.
For around $8, you can't go wrong.
Now I can replay all my old favorites except for Eagle Watch... even Takedown!
http://youtu.be/HLt1b6GJ0FQ
Takedown is actually very, VERY hard... as to be expected from a South Korean game.
The first mission alone involves hostages and a bomb trigger.
It only runs on my XP system, but the old codes from Rogue Spear still work.