Umm, you do know that you can format a 1 gig SD card so that its both Atari and Windows compatible, right? Not sure what version of HDDriver you have to have though. I've got 8.15 (need to update), and it works with that.
Here is a link - read it for the guide. I used it and it worked fine with my setup:
http://www.atari-forum.com/viewtopic.php?f=15&t=15764
Thank you very much for your answer.
I formatted the 512MB SD to FAT via the PC, then I created a partition to my Atari (using HDDriver 7.80), now the SD is accesible from PC and Atari as you said. The only problem I face is that I cannot boot from the SD. So, I boot from a floppy disk, HDDRIVER finds the SD and then I have access to the files inside the SD.
I had experienced hard disk problems with this STE in the past. It's possible that I have the version of the problematic DMA chip, I am not sure.
Anyway, thanks a lot for your advise.
My Atari is a 1040 STE 4MB with TOS 2.06.