This blogger found a way of booting between SimplyMEPIS and Windows and tells us about it.
Read it here
So how did I bridge this gap? By combining 1 and 2. I created a non-active fat 16 partition using Partition Magic. There might be other ways to do it that dont involve 3rd party software, but qtparted in simplyMEPIS wouldnt create a non-Linux fs (surely mkfs would?), and Windows is fairly useless at creating partitions (XP boot disc doesnt have fdisk).