Okay, so I've done quite an extensive search on these forums and also Google as well, and getting some mixed answers.

Awhile ago, I bought me one of these:
http://cgi.ebay.com/MICRO-SD-SDHC-MS...item4aaa823c16

And, I stuck in a regular (not HC) SanDisk 2GB microSD card. I put them together, stick into my PSP 1000 (hacked, running 6.39 PRO NIGHTLY), and it cannot be read. I stuck the microSD card into my other adapter and the PC recognized that it needed to be formatted. I format it to FAT32 and try again in the PSP. Still nothing, just that flashing light.

A guy at GameStop said that if it says "HC" on the card or adapter, it will not work properly. So, when I was going through this forum, I've found a lot of people have been mentioning that Photosmart adapter that takes dual microSD cards. And, I noticed on one of them that they say "HC". However, lots who have this adapter and running dual 16GB cards have had no issues with the PSP recognizing it.

So, is it true that the HC adapter I got off eBay is not compatible?
And, is it true that the Photosmart adapters DO actually work, even tho it says "HC" on it as well?

I'm currently using a 2GB SanDisk UltraII Magic Gate until I can find one that is definitely not going to cause issues.