One option would be transplanting a 2.5 notebook drive into the 5300. I recently did this with a spare 1400 drive re-loaded with system 7.6. The modifications to the hd caddy are fairly simple, but tight. You need to use top-mount screws as there is no way to put in side-mount screws. The caddy is not too hard to drill through. There is just enough clearance when you snap the trackpad panel back on for the top screws. You only need two to hold it, not 4.

The other option would be using another device to load a full OS onto the CF card, then installing in the 5300.

It's a tough device now to refresh, without a built in cd drive and with those deeper, older 750mb hard drives.

Good luck! I pull mine out every once in awhile. The size is great and screens not too bad and the keyboard has an interesting feel to it.