buy it via Steam or DVD Rom?

[W0ef]

You can move your steamapps to another hd no problems, just some steps you have to go through to set it up properly.

This is from the Steam support site:

Moving Your Steam Installation
Warning:

It is highly recommended that you create a backup of your SteamApps folder before attempting this process. Neglecting to do so may result in a loss of all of your game content should something go wrong.

If you're low on space on the drive you have Steam installed, you can move the Steam folder to a different location. Here's an example of how to move the Steam installation between two hard drives:

1. Log out and exit Steam
2. Navigate to the folder where Steam is installed (by default: C:\Program Files\Steam\)
3. Delete all of the files and folders except the SteamApps folder and Steam.exe
4. Cut and paste your Steam folder to the new location, for example: D:\Games\Steam\
5. Launch Steam
6. Steam will briefly update and then you will be ready to play
7. All future game content will be downloaded to the new folder D:\Games\Steam\Steamapps\


Peace!