Technically ( as I understand it) a Cheshire includes a 45deg cutout, as opposed to a sight tube that is simply a tube with a hole at one end and crosshairs at the other. Most Cheshires (eg
http://www.bintel.com.au/Accessories...oductview.aspx ) incorporate a sight tube as well.
A good guide to collimation I have ised is here
http://www.astro-baby.com/collimatio...on%20guide.htm This is a small Newtonion done without a laser.
On my scopes I always noticed that the best results were achieved using a Sight Tube/ Cheshire but to check it each time I used a laser.
Cheaper lasers are often out. My old GSO one was fine in my old 12" but in the 20" produce a noticeable error compared to the cheshire. I now have a Howie Glatter one and it is lovely, bit exxy but!
Malcolm