OK this is getting a bit complicated for me. Are you saying I won't be able to take the files from the Iomega drives and copy them to an Air?
The drives are more than 4 years old.
Sorry for the apparent confusion, but I did not say you cannot copy your files from the Iomega drives to the Macbook Air - your new laptop will be able to read and copy your files on those old drives (regardless of their format which again is likely Windows NTFS or FAT32 - you can plug them into your old PC and determine their format which may impact on whether you want to continue to use them).
If your want to still use the Iomega HDs w/ your new laptop, then their format will be important, i.e. Apple's OS will not be able to write back to the old external HD if it's format is NTFS, but it will if FAT32; for best compatibility since you will no longer be using your PC would be re-format the old drives as Apple HFS+, once you have retrieved all of your old files.
BUT, I made this transition 2 years ago (Windows PC & Dell laptop) to a MBPro & iMac - transferred the files needed from the old PCs to my new Apple machines, then bought new external HDs and formatted them w/ Apple HFS+ (although these can be bought available already it that format if desired) to use as my backup drives. At 4 years of age, your Iomega HDs are now on that downslope of chancing 20% to 50% failure in a couple of years - I would recommend buying new HDs, if cost is not an issue (1 TB Western Digital HDs are well under $100 each). Please let me know if these explanations help; if not, I'll try again and you'll get plenty of great advice at the Mac-Forums - good luck! Dave