I would suspect if the "flat cable" attaches to the drive you'll still need it. If anything, its there for a reason, re-use is advisable.
Understand, some devices won't go for the larger HD as they "limited by design" or bios limits. It is in effect to accept only certain HD sizes or just what it came with. As other posters offered, SSD may not be a good match for your XP based setup. Of course, you can try anything you want, but overall, it maybe a losing fix. Is there a support website, what does it offer or suggest is possible?
I have this old Xplore C2 rugged Tablet loaded with XP tablet edition.
For a long time I want to make a decent image and upgrade with a larger ssd. But I'm unable to boot it from USB. Yesterday I unscrewed the lid and pulled the drive. Its a Hitachi 2,5" Travelmate 40Gb IDE/ATA. It has a flatcable (foil-type) hanging from the bottom-center. It attaches to a connector on the main-board.
Any idea what this is? Can I buy an IDE SDE, write the image to it and forget about this flat-cable?