This would be easy if I were still living with the folks as my old bedroom is virtually a vintage computing museum.

Since moving out - and abroad no less - I have to think a little. Probably a 2GB USB memory stick I brought with me. I shudder to think how much it cost new at the time and perhaps because of that still sentimentally use it over the 16GB+ sticks I've acquired since. Good ol', reliable 2GB USB stick!