I'm not sure why and what your trying to achieve. 1. What version of windows are you trying to install? Setting a primary partition and making it active will become C:. The drive lettering works like this... a. The 1st Partition of the the first HDD becomes C:, b. If there is another HDD then the 1st partiton becomes the next logical letter D: c. continue b. until all HDD's are read. d. Then the rest of the partitions on the 1st drive get the next logical addresses, e. Then the 2nd drives partitions, etc.... So: if you had 2 HDDs, with 3 partitions on the first drive, and 2 on the second then this is what the letters and drives would look like: Drive = D, Partition = P, Letter = L D | P | L 1 | 1 | C 1 | 2 | E 1 | 3 | F 2 | 1 | D 2 | 2 | G NB. If your using NT or W2k you can assign drive letters with Drive manager. 2. Why? i cant see any point in this. 3. I have never heard that. However, After a clean install of windows, you could install MS Office, Games etc on another partition if you hav a small OS drive then this would save space. 4. I have never had this problem ! 5+6. WINS has nothing to do with program files. Program files are exactly that. WINS is an older networking protocol used for 98 machines to connect to a network. Not used nowadays as TCP/IP is far better. Hope this is helpful for you. Also, please ensure your posts are in the right forum.