Different jitter test results on different computers from same router

[videobruce]

There is a site that has a "jitter" test specifically for VoIP service testing;
http://myvoipspeed.visualware.com/
I have Sunrocket and this is the site they use. I'm having 'audio' issues so they have me running tests here.

What I discovered is the "jitter" portion of the tests shows around one full second (1000ms) on my main tower and around 10ms on my Laptop. I have run the test many times and it is always the same. What is really strange is the Laptop is through a wireless card (only about 3 feet away) while the tower is a wired connection.

The tower is running 2k pro w/sp4 and the Laptop is running XP Pro sp1. Both are using Opera V9 if any of that matters. The router is a Westell VersaLink 327 through Verizon.

Any ideas why this "jitter" is 100x worse on the tower?? Here is a test result of the tower:
Speed test statistics ---------------------
Download speed: 2875640 bps
Upload speed: 739200 bps
Quality of service: 99 %
Download test type: socket
Upload test type: socket
Maximum download pause: 7 ms
Average download pause: 4 ms
Minimum round trip time to server: 42 ms
Average round trip time to server: 43 ms
VoIP test statistics --------------------
Jitter: you --> server: 951.6 ms
Jitter: server --> you: 299.5 ms
Packet loss: you --> server: 0.0 %
Packet loss: server --> you: 0.1 %
Packet discards: 0.9 %
Packets out of order: 0.0 %
Number of supported VoIP lines: 12
Estimated MOS score: 3.4

Here it is from the Laptop:
Speed test statistics ---------------------
Download speed: 2271528 bps
Upload speed: 739200 bps
Quality of service: 72 %
Download test type: socket
Upload test type: socket
Maximum download pause: 78 ms
Average download pause: 12 ms
Minimum round trip time to server: 44 ms
Average round trip time to server: 45 ms
VoIP test statistics --------------------
Jitter: you --> server: 7.9 ms
Jitter: server --> you: 11.3 ms
Packet loss: you --> server: 0.2 %
Packet loss: server --> you: 0.0 %
Packet discards: 0.0 %
Packets out of order: 0.0 %
Number of supported VoIP lines: 12
Estimated MOS score: 3.7