Steam Updating, then crashes? Help please?

Please please can somebody help me...

Bought the game via CD from Blockbuster, and then began the process of installing it via Steam.

It seems to have installed ok each time, i think, but then it gets to the update section, and it keeps crashing on 15% complete.

My internet connection is terible, downloading at about 35kb/s, but i've done this 3 times now, and it keeps crashing about about 60 - 90 minutes.

Do i have to install the update via Steam, or now that the game is installed (i think), can't i just go elsewhere and download the 9.0.1 update?

I'm not sure if it has completely installed to be fair, as no icon has appeared on the desktop.

Please help, please?