For the SMB share, yes. Otherwise your only other option is get a fat ps2 and network adapter, or a hd combo kit for your slim, assuming it's a compatable version.
A soley USB based linux install would be horribly slow, USB 1.1 isn't exactly great for data transfers (I have posts about this). I haven't seen anything above 900 KB/s so far, network apparently does much better. Internal HDDs do anywhere from 6.7 MB/s to 40. I would imagine the same speeds for the hd combo kits on slims that support it.
SCPH-39001 V7 GH-019, fliptop case, FMCB 1.8, 80GB HDD (SMS console) 16MB card running it all
SCPH-39001 V7 GH-022 FMCB 1.8, 120GB HDD (Game console) 64MB card running it all