Hi Gabriel! I was thinking that just 32Kb,64kb or whatever are very few for a buffer. I was searching for Mb... Compact flash, that Mr. Karas proposes, sounds good, but I would like to make my PCB as compact as I can, even if compact flash is compact ;) My device is going to be portable. Don't forget that I have to add in the same PCB an FM radio circuit. I found yesterday some nice solutions at this site: http://www.tri-m.com/products/flash.html , but I have to email them for more info.
As for the decoder chip, I am going to use the classic MAS3587F from Micronas. The 8051 derivative will be the EZ-USB FX2 from Cypress. It is one of the best 8051 derivatives I found for my case. It integrates a USB 2.0 core,I2C bus and ports for implementing IDE,ATA/ATAPI protocols,etc. without having to write large codes. So interfacing HDDs, CD-ROMs, compact flash memories,etc. is much easier with this 8051 derivative. It is also fairly fast (only 4 clocks per machine cycle). Cypress also offers a USB mass storage driver for windows. You don't even have to write a USB driver! The only problem is that it hasn't flash memory, so you've got to use external code memory, but anyway small problem for what this mcu offers...