Sound aside, the 4002 is a *very* nice looking turntable, and worth keeping in the system for aesthetic reasons alone. If you search Google for "B&O Cartridges" you'll find several stores that stock B&O cartridges and should be able to provide you with a replacement. I have an old MMC-20EN cartridge that I occasionally mount in my (non B&O) turntable and while the sound is not spectacular, its certainly reasonable. If this is going to be your only analog source, then its probably a good idea to stay with a good lower priced phono preamp. I'm using a Monolithic PS-1, which can be found used for around $200 or so. I know that NAD, Rotel, and Musical Fidelity all make decent, inexpensive preamps as well, so you should have a reasonably wide range of choices under $300.
Ken
Ken