Having successfully setup a low cost NAS, I wanted to find out how fast my NAS was. More so, since the folks at DD-WRT and Tomato worked pretty hard to get USB working on the Asus 520gu. It all boiled down to Samba versus Windows. The results were an eye opener!
Objective:
To determine network access speed on an external USB drive attached to Asus WL-520gu running Tomato with Samba versus access speed on the same network, when accessing a Windows share on a PC running XP.
Setup:
Asus WL-520gu flashed with Tomato V1.23
Sandisk Cruzer 1GB USB flash drive, FAT32
A windows share on a PC running XP, NTFS
Yeah ok, FAT32 with NTFS! I don’t have a high tech lab here, I make do with what I have! 
Results
Flash drive attached to router (Test I)
Windows share on a PC (Test I)
Flash drive attached to router (Test II)
Windows share on a PC (Test II)
Conclusion
These are actually very surprising results! The flash drive attached to the router actually performs better than a native Windows share!