SNES/NES is emulated in any way, only GBA games play natively from slot-2. If you don't need GBA support, an emu on a slot-1 cart will do just fine.
Personally, I have an AceKard 2.1 in slot-1, with GB/GBC/NES/SNES emus running off it. Since you got a DS Lite, an AceKard 2.1 will do just fine, no need for a DSi-compatible one.
For GBA games I have an M3 Perfect in slot-2. Nowadays it's hard to find, the EZ-Flash recommended by akfgftw is probably the best choice nowadays.
This post has been edited by dfkt, Tue, December 7th, 2010 at 13:27