When you're starting out in business, it's very hard to tell how big it is going to get and picking your computer equipment, including peripherals such as printers, is something of a lucky dip. But it needn't be, if you pick a printer which can expand within your organisation to keep up with developments. Lexmark's T642 majors on expandability, though even in its base configuration it's a very useful workgroup mono laser printer.

Conventionally designed, it has a large, 500-sheet paper tray at the bottom and an equivalent output tray set into its top surface. A 100-sheet multi-function tray pulls down from the front panel and a combined drum and toner cartridge slots in easily when you hinge the whole front panel down.

There's a backlit LCD display for status information, big Start and Stop buttons and - unusually - both a USB 2 socket and a number keypad. Both of these last two items have special functions. The USB 2 socket enables you to bring documents to the printer on a memory drive, browse through them using the LCD and print them out from the printer. The software supports PDF, TIF and JPG files, though oddly not Word documents.

The number keypad is used for a Lexmark facility called Print and Hold. This enables you to start a print job from your PC, but only have it actioned by the T642 when you get to it and enter your four-digit PIN code. The idea here is that you can print sensitive material, even when you're sharing the printer among several people in a workgroup.

A list of accessories you can add to the printer gives some idea of how versatile it is. You can fit an extra three 500-sheet paper trays, or a 2,000-sheet bulk tray, and a duplexer. It's slightly surprising there's no duplex facility already built into a mono laser printer costing over £500, though. On the output side, you can add a mail sorter, up to three output bins and a stapling finisher.

Oddly, for a printer designed to be very expandable, the only connections supplied as standard are parallel and USB 2: you have to pay £120 extra for the T642n to have networking built in.

Output quality is generally good, with clean, spatter-free text and reasonable business graphics, though greyscale images, such as photographs, suffer from some banding in areas of tone and are not as smooth as they might be. Trying to print on the second side of pages, by using the manual duplex facility within the print driver, also caused some pages to crease on our review machine.

We calculate page costs to be just under 1.5p per page, including 0.7p for office paper, which is quite reasonable for a printer in this class. Overall it's a good choice, particularly if you feel you'll need increased capacity from your business laser in the months to come. The upgrades aren't that cheap, but they're still cheaper than buying a new, bigger laser printer from scratch.