Jean, you can of course download and install as many XAMPP versions as you like.
Just install each to a different named folder as XAMPP does not rely on the registry until, that is, you install a Windows service, for example xampp163a - xampp170 - xampp173 etc. get the idea?
Your 1.7.0 version would remain with the default folder name of xampp so it is easy to determine which is your currently preferred version and all the installed versions can be on one partition or drive.
I have installed on various drives and partitions all releases from 1.6.3a up to the latest 1.7.4 (yuk) that I use for testing and trying to solve issues that arise in these forums.
I found upgrading to be too much of a hassle for the very limited benefit achieved, if any - example, this latest 1.7.4 offering.
I am using mostly 1.6.8 as I don't need the latest component versions for scripts etc. that I develop for production but it's nice to be able to easily test scripts using the various new component version releases as they arrive in XAMPP.
Obviously, because of port and other conflicts, you can only run one version at any one time...
...and I totally agree that if you are happy with 1.7.0 then stick with it especially now you have ironed out your 'moving to a new computer' pains.