There are several updates (service packs) available on the Autodesk website. This update does fix a few crash issues. Update 2 does include update 1, therefore there is no need to download and install update 1.
Update 2 for AutoCAD is available, click Here.
There is a separate download for 32-bit and 64-bit versions, please download the applicable version for your operating system. To see which one you have right click on My Computer and select properties (Start->Control Panel and double click System) and if it doesn't say 64-bit on the General tab, then you have a 32 bit system.
If you have a vertical program like Civil 3D 2009 you can check on an Update availability by going to www.autodesk.com/support and select your program from the "Select a Product" dropdown list, then select Data and Downloads->updates and Service Packs on the left sidebar menu.