Yes, that is the M125 Serial Hotsync Cable. As long as you ordered a logging cable made for a PDA it will plug right in. The Serial Hotsync Cable has a female connector, whereas a notebook/laptop computer would have a male serial port.
The guy I bought my logging cable from on eBay included a null modem connector for $5 extra that would allow you to use his cable for both a PC or PDA.
Quoting mountaineerjeff:
this? if so wouldnt I need the 'laptop cable' not the 'pda cable'? the laptop cable would have a male end and the sync cable is female