May I recommend a read through my recent thread on changing the A/C compressor on my 99 Buick Park Ave. 99 Park Ave Leaking A/C Compressor
I did a lot of research on some A/C Forums and came to the determination to use the OEM brand (Delphi) compressor.
Be sure to replace the accumulator and orfice tube for warranty coverage on the compressor and optimal system performance.
Flushing the system if your compressor was seized up is critical. The condensers on these cars are parallel flow and very difficult flush, not something the backyard mechanic is capable of. I would recommend an in line filter if you find lots of metal shavings in your orfice tube screen. In my case the compressor was not seized so I didn't dwell on the flushing process as much.
Auto-zone claims to carry the flush gun, vacuum pump and gauges, but I had a family friend who evacuated (vacuumed out) the system and charged it for me.