I've actually had numerous problems with my canon scanner under windows. Actually, I've had problems with my previous scanner too (both were Canons)!! It was driving me NUTS! Canon drivers can really be nightmarish. If they work, they work, but if there is some conflict with another device or something else in your system, hope to have a LOT of free time on your hands (to either bring the machine back to the store or... reinstall windows... hoping that'll fix it!)
Wireless and scanners are definitely a weak point under Linux, unfortunately. Printers are usually ok (eg : you can buy a fairely recent Samsung ML-2510 printer, pretty cheap, linux compatible). As Edvard pointed out, it is usually possible to find hardware that'll work... even scanners, but that could mean not buying the latest and greatest... HP is generally
moderately good at that; see
http://hp-linux.cern...port/devscanner.php3 and
http://hplip.sourceforge.net/ -- Hewlett-Packard's Officejet are usually pretty well supported.