Fearangel,
I am far from an expert,,,,,but my Download Master has worked perfectly right out of the box. What I did:
Using 1.9.7.2 firmware from Asus.
Partitioned my 250g USB drive as a single EXT2 partition.
Plug in the drive to the router. The router saw it immediately.
I set the router to "Share all partitions on this drive".
To access it through XP I go to "Network Places". It shows up as "part0".
I've installed the Download Master software on all PC's in my network and tested each one. All worked perfectly.
In fact just last nite I used Download Master to grab a 500mb ISO. I guess I've been lucky Now the transfer from the USB drive to my CD-R was slow like everyone else has stated so I just started it and walked away.
I do believe the key is the type of partitioning you do. If I'm correct the router firmware is Linux(?) based and may not recognize the NTFS partition. I had to dig a bit to find a way to format with EXT2 but I was fortunate in that my job uses a bootable Linux distro that does this. Also from reading the forums I believe (again I may be wrong) that your FAT partition will be limited in the size of the download you can do--2 mb I think.
Good Luck.