all your data is associated with your steam account. you can install steam on new computer and login with your current name/pass. you will however have to re-download all your games in your account and lose your custom content (maps, models, etc). What you can do alternatively is copy your whole Steam folder from old computer to new computer, delete the clientregistry.blob file, and then start Steam. Log in and you be fine. (Or install Steam and copy just the /steamapps/ folder).