Maxtor does Quantum HD support. A utility can be installed to overcome the 8.4 Gig "limit". Their support area says:
Disk Manager is a hard drive installation utility for overcoming BIOS capacity limitations on PC systems. It intercepts BIOS Int13h calls and allows systems which do not support LBA or other extended translation to give users the full capacity of their ATA hard drive. It can also be used as a convenient partitioning and formatting tool for your hard drive.
Please be advised: Maxtor no longer licenses the Ontrack® Disk Manager software and it has been removed from our software download page as of 8/28/01. All new drive installations or existing drive reinstallations for Quantum® ATA hard drives should be performed using Maxtor's MaxBlast Plus (v1.27S or newer) or MaxBlast Plus II software. The MaxBlast software can be downloaded from Maxtor's Maxtor Software Download Page. The contents of this FAQ are being provided strictly for troubleshooting and/or reference purposes for the support of customers who have installed their Quantum hard drive with the Ontrack Disk Manager software prior to 8/28/01.