The most important facet of a scanner's specification is image quality and it was disappointing to see that although several of the scanners we looked at were very fast, image quality appears to have been sacrificed for speed, even with some of the USB 2.0 scanners.

The best image quality of the bunch belongs to Canon's CanonScan D1250 U2F, and while some of the scanners here are nearly as fast, none come close to the Canon in terms of image quality.

Both the other USB 2.0 scanners, the HP ScanJet 3570C and the Visioneer OneTouch 9000, were disappointing in terms of the quality of colour, transparency and slide scans. This was particularly disappointing with the Visioneer OneTouch 9000, as it uses the USB 2.0 interface to full effect and is lightning fast.

Three remaining units, the Microtek Scanmaker 4800, the Visioneer OneTouch 8920 and the Umax Astra 4500, all suffered from poor handling of transparencies and slides, the worst offender being the OneTouch 8920 which suffered from poor management of colour scans as well.

Despite its slow performance, the Umax AstraSlim produces reasonable quality scans; maybe not good enough for business use but certainly fine for the home. Its low price is also attractive.

Overall, the Microtek ScanMaker 4800 is the best of the rest after the Canon unit. It's not perfect by any means, but it's a good compromise if you can't afford the Canon.

If you're just scanning documents on a limited budget, then the Umax Astra 4500 is worth a second look, as at low resolutions (which is all you need for document scanning) it is surprisingly fast. At the other end of the scale, Umax's AstraSlim is worth looking at for home use; it offers reasonable scans despite being painfully slow.