Windows 2000 Service Pack 4 is a security and features improvement for Windows 2000, compiled and distributed directly by Microsoft. It allows Windows 2000 to run a wider variety of software more effectively and safely. The Service Pack can also be installed via the network from a host device, although this is somewhat slower than many Internet connections would provide with other software downloads. Note, though, that Service Pack 4 only works properly with Service Packs 2 and 3 installed as well.