To install your video card drivers just go to either
http://www.nvidia.cm or
http://www.ati.com seeing as how you probally have either one of thoose, go to their driver sections and follow their instructions, when you do download the driver.exe it will be a simple install then restart of your PC.
To install the MohAA patches simple take this link
http://www.ultimate-gamer.com/mohaa/mohpatches.htm and download 1.1, install it and reset your PC just for good measure (You don't have to though.) and you should be good to man.
Have fun.