From BeeSync Technologies:
FramePad is a network protocol analyzer for Windows 98/NT/2000/XP. It allows you to examine data from a live network or from a capture file on disk. You can interactively browse the capture data, viewing summary and detail information for each packet.
Work with multiple documents.
Run multiple captures simultaneously with different capture filters.
Open and edit large capture files up to 100 MB in size.
Search for packets containing string or data pattern.
Search for packets using the predefined filters.
Save and load filters from file.
Use protocol variables to define a new filter.
Use hardware filter flags to limit type of frames captured.
Use bookmarks to mark network frames in documents.
Start and stop multiple running captures with one command.