Well Toby, the fact that you have backup software installed already then you're well on your way to protecting your data, so you're in no way a dunce.
I'm not familiar with Roxio BackOnTrack software so I don't know what its capabilities are, so I can't give you a comprehensive explanation from that aspect. If it can do a complete system backup, and you have enough DVDs, then do that the day before your techie guy arrives.
I tend to do my backups manually, so I don't use any backup programs. If you have an external Hard Disk drive attached to your PC, as I do, then data backup is so much easier and quicker to do than burn to CDs/DVDs. However, as you are using the DVD method then stick with that for now.
I would start making a list of all the data you wish to preserve and the locations of where they are currently stored. Most programs you install on your computer usually save Profiles and data you add to the program in a sub-folder of the main program. Check the preferences sections of your software to see where they save data, and/or browse your PC in Windows Explorer to see where your important data files/photos, etc., are stored.
Using your Roxio BackOnTrack software don't forget to include the folder where all your emails are stored. Depending on the particular email software you use, they are usually automatically saved elsewhere, sometimes in your USER folder.
You can also backup your Internet Explorer Favourites folder where all your bookmarked websites are stored.
For your most precious files, e.g. Photos and documents, I would do a separate backup of those, independent of a full system backup.
Make sure that you have the most up-to-date version of Roxio BackOnTrack software that is compatible with Windows 7. If it's not, you may have trouble installing that program on the Windows 7 system and therefore be unable to restore all your saved data from your DVDs. That would never do.
If you have purchased any programs from the Internet as an electronic download, make sure you back them up as well.
No doubt George will best be able to advise you on the locations of the IG Pro data files for your backup, and other members may be able to offer additional, or alternate, suggestions for your backup process.
I hope this is of some value to you Toby.
Laurie.