But as you observe, it will be unequal. The reasons why far exceed this small space. Instead I'll note that IP SHAPING if you want to implement it can be done with a Linux based PC with a pair of ethernet cards and a week of your time configuring it to replace your router.
In theory the bandwidth is equally shared, but reality is that packet sizes, response times of the host machine that is serving up the content will tilt the results. Also, some firewalls on the PC/Mac add their baggage.
Best of luck,
Setup:- Main computer with Windows XP Pro SP2. Internet Connection Sharing with Ethernet ADSL modem connected to wireless router. Main computer connected to the wireless router(D-Link Dl-714P+) by CAT 5 cable(i.e 10/100). Two other computers connect by wireless(802.11b), one Xp Pro SP2, the other Xp Home SP1.
Observation: Main computer alone is able to connect at over 800kbps over a 1,000k ADSL line, although sometimes can drop to 700kbps. With one other computer connected wirelessly, connection of the main computer drops to some 550kbps, and with two computers connected wirelessly, connection of the main computer drops to less than 150 kbps ! The computers which connects wirelessly is a bit faster, at some 50kbps to 100kbps faster. Is this normal ? i.e. is the ADSL line shared among the three computers, with each getting part of the bandwidth ? Thanks.