Printers:

HP Compatible Laser or Inkjet (for full page receipts and reports)

Epson Compatible, parallel port, 40 Column Receipt Printer (for POS receipts) (the Epson TM U200 is a good choice for a dot matrix printer, the Citizen IDP 3210 is a good thermal printer)

Cash Drawer:

Any drawer that is triggered by an electrical pulse from receipt printer, or any manually triggered drawer.

Bar Code Reader:

"Keyboard Wedge" type.  The bar code reader plugs into the computer where the keyboard normally plugs in.  The keyboard and barcode scanner both plug into the wedge.  The wedge decodes the bar codes.  The scanner can be a pen type device, a CCD device or a laser scanner.