The problem: When I connected my N800 to my computer by USB cable, the computer would not "see" the 4GB SDHC card in the N800, just the mini-card that came with it. This would not allow me to download files from the computer directly to the SDHC card.
The fix: This is a little convoluted but follow along. Microsoft has a hotfix for this: KB934428. This is not fully tested so there is no download button for it on the KB934428 page. You have to send an e-mail to microsoft support requesting the fix. To get the fix, go to this link:
and enter your information. It worked for me. YMMV.
It didn't fix the internal card reader in my computer, but now I can see the SDHC card in Windows Explorer and download directly to it when the N800 is attached.
And make sure that you get the right language version, if you are using a non-english XP - thanks to the way MS botched their il8n, only the matching language version of the patch will install.
My solution to the problem was to buy a Sandisk SDDK-113A10 SDHC card reader for my 8GB Class 6 cards in the N800. Simply plug them into the USB adapter and Micro$notXP thinks you have an external hard drive, and treats it accordingly.
Works great...real fast.
With the recent SD card software bugfix in OS2007, I figured it was better to put the files on the card directly, rather than letting OS2007 handle it. Once you figure out how to pick the edge of the card out of the non-spring-loaded N800 slot, it's easy. Sandisk SDDK-113A10 is $13.98 including shipping from cellmem on Ebay Stores.
I don't have time to correct Micro$not's defects on all my friends computers, so I just carry the SDDK-113A10 in my N800's Sony PSP carrying case. That way I can just plug it in around this problem, anywhere.