Sorry if these questions have been asked before, but I am struggling to find the right info in the right place?
Yes, this question has been asked literally thousands of times. A google or LQ search for will turn up hordes of hits.
The basic strategy though is to install Windows first, on the first primary partition, then install Linux (BTW, I suggest getting a more recent distro than Redhat 8.0, which is rather ancient (must be what, 2001/2002?)). As you have a cable modem it shouldn't take too long to download something more contemporary). I don't know if your modem works with Linux (have a look at the LQ HCL
), but a more recent distro will have better hardware support than RH8.
So the first partiton will be ~6gb, the second will be an extended covering the rest of the drive. Partiton 5 would be your swap (400-500mb), and at least one more partition for Linux. However, it's a good idea to put /home on a separate partition, so you might use a 50/50 split of the remaining space for / and /home. This will let you try a few distros without losing your /home stuff. Then again, modern distros can quickly chew up 3gb so leaving at as 1 partition might be better (and, of course, you can back up /home to the Windows partition if you do want to reinstall). Some people use a separate /boot, but I haven't found it to be very useful.
As Windows' fdisk is garbage, I would use Linux to create the partitions (but don't actually install it yet), then install Windows, and finally Linux (Windows will overwrite the mbr without asking, which is why we install that first).
As for sharing a partition, apparently there is some tool that allow Windows to read ext2, but I don't know what it's called or how well it works. However, Linux can read and write FAT32 just fine, so you could just use the Windows partition as a share.
You will need to configure the boot loader to boot Windows, but most distros will detect the Window installation and set up the boot loader automatically.