Adaptec still sells the 2940 Ultra for $275. I found one at a thrift store for $4! It's a really nice card but keep in mind that its slowest transfer rate is 10 megabit/second so older SCSI devices that can't handle 10 will not work reliably with this card.

I have an old 233 MHz A-Open with upgraded hard drive (15 g) and 128 RAM. I am trying to get a CD writer working that calls for a SCSI adapter card with 50 pin internal connector. The CD writer is a Sony CRX140S. Will this card get me going?

Hi, according to the Sony site, your CRX140S is a SCSI-2 device:
http://www.storagebysony.com/cd-rw/product.asp?id=55

The Adaptec AHA-2940S76 would work fine for you. 10 MB/s which should be plenty. If you want a little better performance, you can get the 2940AU which we also sell. You will also need an internal 50-pin cable from the SCSI card to your CD writer.