Definitely a MacBook. Macs are built with media, music and design in mind, and handle the load of tweaking and recording large .mp3 and other music files well. Unlike some PC brands (though certainly not all), Apple didn't skimp on the peripherals, so the inbuilt speakers and sound cards are more than passable.
MAC G5 is the best computer for recording and mixing sounds. It contains 2GB of RAM and a great video graphics card and a great sound card which will solve all the problems of being installed by drivers. There is no need to install any separate driver in the system.
The best computer is any Apple Mac. These computers come with free applications of GarageBand, itunes and i-photo that can help record, mix music and make corresponding art.
The best computer for recording and mixing music is an Apple iMac. The music software Garageband that comes with the Computer helps you record even minute music and mix music as you like. The output quality is so good that, you will never regret for the purchase of the Computer.
I use a PC... I can record large songs in 24bits at 96khz, no problem. I can't understand why people automatically say MAC? I still haven't heard why MAC is better.
While any computer with a high-quality sound card and a powerful chip set can do this, you're best off with an Apple. If you want something portable, the 15-inch MacBook offers all the power you'll need, plus already-installed software that's great for amateurs.