You should also factor in that swap/page files will burn out any flash-type card. Such files have the tendency to rapidly write and rewrite data onto the card. Also, while the write properties of these cards are extremely high, the designers more than likely intended normal file writing to this technology.
If you go this route, expect your card to be non-functional within a few weeks (or a few months max).
I've seen people using this method to gain additional virtual memory. This was especially prevalent with the Sharp Zaurus crowd awhile back. Although the Zaurus runs Linux and uses swap and swap files, the concept is very similar to how Windows uses virtual RAM. IMO, its not worth it, unless you've money to burn. Cost-wise, its probably better to just add more physical RAM.