I agree w/Alt909 - midiox is a freeware/shareware utility that will save hundreds of thousands of sysex dumps from an SR-16 in a gigabyte of hard drive space.
Get it here and even if you don't know how to use the many other tricks it can do, keep it around because it is a VERY handy little tool.
The Alesis data disk is fine, but it's old technology and requires 3.5" floppy discs to hold the sysex info.
You already have the computer and if you don't have a midi interface for it, get this one. When you upgrade it can still be used as an extra midi in to your system --- in other words, it won't conflict with a USB or firewire audio box that you add to your system at a future time.