Hi !! The T42 will work excellent with a mSATA to 44 pin IDE adapter and mSATA SSD drive.
First, be sure you have the latest bios 3.23 - if not flash the bios to 3.23 version, you will need a usb 3,5' floppy drive adapter to do that.
Search ebay for "mSATA to IDE" and you will find several alternatives, ranging in price from $4 to $30. some of them will fit directly into the 2,5' hd caddy, orhers will also work but ( the $4 ones) is more difficult to fit. In addition you will need a mSATA hard drive. Speed will be limited to IDE 33 mb/s from the ide bus found in the T42, BUT: due to the mSATA SSD's low latency time and the capability to 100% utilize the capacity of the IDE 33 mb/s bus speed, the performance when it comes to everything related to disk operations is enormous. even if the T42 is very old, the quality is up to day unmatched. I use a T42 as a chart plotter for my boat, running Linux and OpenCpn and the performance is far better than a new laptop with w8.1 running OpenCpn, the reason is that the Linux is so much more suited for the job than w8.1,,,,,