9 files:

Model:	mk550
Vendor:	LOGITECH
Version:	3.81
Filesize:	621 KB
Operating system:	Win 7, Windows Server 2008 R2, Win Server 2008 R2, Win Home Server, Windows Home Server, Win XP
	Download file

Model:	mk550
Vendor:	LOGITECH
Version:	7.99.23
Filesize:	7 MB
Operating system:	Win Me, Windows 7, Win Server 2003, Windows Home Server, Windows 98 SE, Win 7, Win XP
	Download file

Model:	mk550
Vendor:	LOGITECH
Version:	0.18.53
Filesize:	9 MB
Operating system:	Windows NT, Windows Server 2008 R2, Windows 2000, Win 98 SE, Windows 7, Win 7, Win XP
	Download file

Model:	mk550
Vendor:	LOGITECH
Version:	4.54.11
Filesize:	2 MB
Operating system:	Windows NT, Windows XP, Win Server 2008, Win 98 SE, Win 7, Win XP
	Download file

Model:	mk550
Vendor:	LOGITECH
Version:	9.52
Filesize:	652 KB
Operating system:	Windows 7, Windows Home Server, Win 7, Win XP
	Download file

Model:	mk550
Vendor:	LOGITECH
Version:	2.19
Filesize:	35 MB
Operating system:	Win Vista, Win Server 2008 R2, Win XP, Win 7
	Download file

Model:	mk550
Vendor:	LOGITECH
Version:	6.50.25
Filesize:	7 MB
Operating system:	Win Me, Win 2000, Win Server 2008 R2, Win 98, Windows 95, Win 7, Win XP
	Download file

Model:	mk550
Vendor:	LOGITECH
Version:	3.57.95
Filesize:	6 MB
Operating system:	Win Me, Windows 98, Windows 98 SE, Win 7, Win XP
	Download file

Model:	mk550
Vendor:	LOGITECH
Version:	8.90.74
Filesize:	8 MB
Operating system:	Windows 98 SE, Win 64-bit, Win NT, Win 7, Win XP
	Download file

PNPID:
PCI\VEN_6DEC&DEV_AD2E&SUBSYS_7AE7BD6B&REV_02\2&4684EE57
PCI\VEN_6DEC&DEV_D320&SUBSYS_9EBB7A9E&REV_07\9&AC1CAF81&9&49D9
PCI\VEN_6DEC&DEV_970B&SUBSYS_C49E1729&REV_05\6&CD051F4F&6&3AF2
PCI\VEN_6DEC&DEV_D820&SUBSYS_B5288FD6&REV_09\8&C65AED3E&1&570D
PCI\VEN_6DEC&DEV_C1AB&SUBSYS_80E7939B&REV_04\2&837CA7A1&6&6C5E

Supported OS:
Windows 98, Win Server 2008, Win 7, Win XP, Windows Server 2003, Win 95, Win Server 2003