Can't help you with Linux, but it's probably working the same way as with Win2000.
Basically : It's not about hardware, you just need 2 machines with enought HDD space and stuff all required for good server.
Then you assign IP addresses, twice : for each machine and the whole system. You may also want to have good connection between these serevers. Then you assign under what conditions user requests are sent to another server.
In W2K Adv load balance is built-in running as service , don't know about Linux ...

How exactly to do that ? You'll have to dig some books & check the web. It's far beyond forum thread. Some call it art  

Good luck
Chef