I really want to buy a card like the M3 DS real or the R4 DS but I don't know which ones are compatible with the old nintendo DS. They all say that they work with the DS lite. Also, if I get one can I get games on it from online for free or cheap? I'm a cheapskate.
all slot 1 flash card will work with nds and nds lite. games are all over the net, just google nds roms i suggest you dont buy the r4. go for edge, supercard, acekard, etc etc, see here for reviews http://gbatemp.net/?dynamic=8
You were saying you were looking at the m3 ds real. That's what I have, and I couldn't recommend it enough. It's a great card to have, any newb (not saying you are) can get it, and figure out how to use it in about 10 minutes. It's extremely easy to use and works great.
I agree with the above, the M3 Real card is the one to get, you get fewer compatability issues with it than with the R4. If you write to them with issues, you get a response and the software is currently updated every 6 weeks or so to eliminate the issues