Depends on your price range, for the USA:
PowerTellecom R4000 - 4 channel Budget DVR with Client LAN Software, great quality, very stable. Used one for a while personally and have several clients with them and no issues.
AvTech 4 channel - 4 Channel Budget DVR with Removable HDD, USB, and Browser Based LAN software. Once again stable system, remote video software is limited but if you need a budget DVR with browser based, such as for DDNS, this one works. Got one sitting right here for past couple months, just works.
Active-Tek 4 channel DVR - also sold under Eclipse CCTV as Nubix, Uriel.net as TM400, and several others. USB, MPEG4, 120pps, DDNS, and then some. Great mid range 4 channel DVR. Optional CDR also. Have only used the remote software myself but several colleagues in the US sell them and have had great results.
GE StoreSafe 4 channel - rock solid with full featured client LAN software, same software used in their more advanced units. More advanced would be the StoreSafe Pro, StoreSafe Pro-2, DVMRe-CT, and DVMRe-PRO. Used and sold many of these, no issues at all.
DM is a waste of money on the US side IMO and I would stay clear of it, doesnt match up to the GE DVRs and costs more. Used the DM also.
Bosch has some decent units coming out.
Sanyo also has some decent 4 channel DVRs though for the extra couple hundred $$ i would buy the GE StoreSafe.
Panasonic has some high end units but complicated to set up, and a heavier price tag than the others.