….Please let me know which memory cards are compatible with Nikon D40-SLR ? What is SDHC card ? What about SanDisk 4GB SD High Capacity card with Reader – compatible only with newer SDHC Cameras ? What about Panasonic Pro 2- GB memory card or any better suggestions i.e. card having better storage capacity i.e. 4GB or 8GB, Quality / Brand, Speed /Performance & PRICE – that should be compatible with Nikon D40 SLR.

Per the NikonUSA website at
http://www.nikonusa.com/template.php?cat=1&grp=2&productNr=25420

The D40 Storage Media: SD memory card, SDHC compliant .

So the D40 will accept a "secure digital high capacity" (SDHC) card.

Any card which meets SD or SDHC specs should work in the D40. The fastest cards are likely to be the SanDisk Extreme IV cards or Sandisk Ducati cards.