Mine was a Palm IIIc which I still own and love although it is not Windows Vista compatible like so many of my much loved software and such.
In fact I think that being unable to connect to my IIIc led to me purchasing my first 'real' ebook reader, my Sony 505 last year. I did briefly use my DSLite with one of those R4 cartridges but it didn't compare and I quickly moved onto my 505.