I planning to install Linux OS and i heard that configuring modem is tough job. Therefore, i post this message in order to get some help.
I using Mandriva 2007, FC 5 and Knoppix 3.6 . My internet connection is Broadband and have a unbranded modem. Help is greatly appreciated. Thanks in advance.

Is your modem a USB or ethernet modem?

You "are using" these distros? What do they say about your modem?
Have you even attempted to get the modem working?

How are YOU connected now? Are YOU thinking about trying to configure a PCI internal modem? Broadband requires an ADSL modem. The better units have one telephone line in <RJ11> and a minimum of one Ethernet cable out <RJ45>. Some have one Ethernet out and one USB out. See here...www.wiki.com and http://tldp.org/HOWTO/HOWTO-INDEX.howtos.html Let us help. By posting YOUR data, we can find the answers together.

Meaning Peter_APIIT (OP) I guess... if you want to emphasise words, try italics. (Otherwise you read like an infomercial or worse: a TV evangelist.)

Peter_APIIT: How are you getting on?
... at posts = 224 (reading your stats at time of writing) you've been around enough to know the score: no help is available without details. You know the kind of details needed by now - so why with-hold them?

Meanwhile - for folk googling here:
For trouble-free internet out of the box, I suggest basic serial hardware (external) modems for dialup and ethernet routers for ADSL. Then, provided your mobo is supported, the connection will work out of the box.

Some mobos do not have a serial connector. USB-serial devices are available to get around this. I know of none that require special drivers in linux.

Some mobos have special ethernet cards (I'm thinking of certain nvidia chipsets here, but they are not the only ones)... an additional pci ethernet card will be needed.

Internal dialup modems are well supported, but it seems the one you actually have is the one which has no support. Check them out with the scanModem script from the linmodem project pages.

USB 2.0 compliant devices should be supported, but many firms seem to want to lock you into their product line by including some special firmware.

Wireless routers require ndiswrapper - doesn't come with every distro. It is better to have some sort of direct access if you have a choice.