Sure thing - Linux versions 2.4.22 and above will fully support bandwidth limiting services without a problem.
I've actually successfully implemented such services for a number of customers using Linux Fedora Core 1 and 3.
We actually plan on covering bandwidth management at some point as its a major chapter and something that requires a lot of studying and work in order to get working correctly.
Basically you create discipline queues (qdisc) and and classes which are used in conjunction with various bandwidth management algorithms ( HTB, CBQ e.t.c) to provide the management you require.
In addition, IPTables comes into the game to help mark specific packets which need to be treated in a different manner such as high priority.
Here are some references - they might not make any sense if this is the first time your reading up on the topic:
luxik.cdi.cz/~devik/qos/htb/manual/userg.htm
www.linux.com/howtos/Bandwidth-Limiting-HOWTO/index.shtml
If there are specific questions, I'll be happy to answer them.
Cheers,
