I have had success with the 8 GB Transcend 133X in my H320. It has worked perfectly - no problems of any kind.
I also have used the 32 GB Transcend 133X in it. At first the 32 GB Transcend was finicky, sometimes freezing up. I gave up on it and got a 32 GB RiData 233X card, which has worked perfectly so far. Then this last weekend I tried again to get the Transcend 32 GB card to work. I reformatted it and loaded the 2008-12-23 version of Release 3.1 (I had been using a version from last summer). Now it seems to be working, so maybe I had gotten a file corrupted on the card.
Bottom line, I can vouch for the 8 GB Transcend 133X.
Take note of the speed of the cards you consider. Any are fast enough to record audio to, but the faster the card is, the quicker it will upload or download files to and from it. The A-Data Speedy is not as fast as the Transcend 133x; I recall it clocks in at about 40X. Others on this website have had good success with the A-Data Speedy CF card series, so it seems a good bet.
Also take note that you will have to have a functioning hard drive for the H320 to flash the CF-mod bootloader from the wiki page here. It cannot read the CF card until you have flashed the modified bootloader to it first. You have to do that from its hard drive, but you say that anything you record onto the drive is corrupted. If it were me, I would be cautious about using a possibly corrupted hard drive to flash the bootloader, because if it doesn't work, you could brick your H320. You can find replacement Toshiba MK2004gal drives on eBay for about $25-30. Avoid the ones with the Apple logo on them, since some people have found them incompatible with iRivers. Apple apparently modifies them in some manner.
Good luck! I've been pleased with my CF-modded iRivers.