Hi! As quoted above, getting data out of these patient monitors is "not trivial". So I just wanted to spread the word that I just released a small commercial off-the-shelf product that saves you from re-inventing the wheel:
http://www.medicollector.comUsing MediCollector, you can quickly and easy stream data from Philips patient monitors onto your hard disk.
(Sorry for the commercial, but I think its relevant on this thread!)
As a Philips employee, I can't endorse 3rd party applications we have not tested, so unfortunately I can't say "great work!" because that might be construed as an endorsement

Here are the model numbers for the MX400-550 so that you can update your supported device page:
MX400 - 866060
MX450 - 866062
MX500 - 866064
MX550 - 866066
You may also want to note that with MX400 - MX550, it is recommended to use one of the ports provided by the J13 RS232/MIB Interface board. The RS232/+5V port on the J40 Advanced System Interface has a different pin-out, and the cables you offer may not be compatible with that pin-out.
For future enhancements, you may want to consider adding support for MP2/X2 via LAN data export, which uses the same packet based protocol on UDP/IP. This would, of course, only be useful in a non-centralized environment.