I would suggest to assemble a pc then going for a dell or an HP, here are the General recommendation
Processor : - AMD 64 bit dont go for intel, unless you are going for the new dualcore core if not clawhammer is the way to go.
Motherboard:- MSI is good and cheap find one with a SATA contoller and IDE controller so that when you run out of sapce you can have more hardisk and with SATA you can mirror your hardsk to back up incase.
Soundcard:-MSI comes in with a builtin soundcard but if you are a music person get a creative sounblaster anything that has a 5.1 atleast will do
View Card:-I won't recommend any built-in Video card get a ATI 128 MB so that you can play online games.
Your Enthernet card should be built in in your motherboard if not try anything from that says realteck.
Ram:-you at least need 512 MB of ram but 1GB is recommended, i have two GB.
Thats the basic configuration
Take care