I have a Vista operating system and have have tried to insall my "Half-Life 2 Episod One" software programs. I have installed the Half-Life 1 Anthology and Half-Life 2 programs without any problems. However, when I try to install HL2 Episode One I get the following error message: "There is not enough free drive space to run steam". I uninstalled steam and the two other Half Life programs and reinstalled Steam. When I tried to just install the HL2 Episode One by itself I got the same "not enough drive space" message. I have 184 GB of free space on Drive C where I install my software and 254 GB of free space on Drive D. Hope someone can help me with this problem soon. I tried to get help at the Steam support center but haven't received in reply to my help request in 3 days! Still waiting. Thanks. Thank you!