- Put the install disc into the DVD drive, share it over the network, and install from the UNC path to the shared drive. Or...
- Mount the ISO image file as a drive and share it over the network, and install from the UNC path to the shared "drive".
#2 is by far the fastest and easiest. "Fastest" is a somewhat conditional term. Qualifying that would be to say that it does take a little more time to mount the file and share it out than it does to insert a disc and share it out. But after that minor step, the performance contrast is enormous. The read/fetch performance of a modern SATA DVD-RW drive is no match for read/fetch performance on an internal SATA hard disk.
I wish Windows 7 would have added native support for mounting ISO files as drives. I was hoping that maybe NET USE or MOUNTVOL would add this capability, but alas, it has not happened. But fear not, you can use any of several freeware or shareware utilities to mount an ISO file and it's easy to do. One is UltraISO, another is Virtual Clone Drive, but there are others.