(VERY rough finger-in-the-air estimates here)
* install Windows (30-45min)
* install all necessary drivers (~30-60 min)
* install latest available service pack from offline media (~45 min)
* install latest available IE from offline media (~20 min)
* run Windows Update, install everything
* repeat previous step 6-7 times until no updates available (1-2hrs minimum)
* install browser, media player, email client, chat client, etc., and remove/disable MS options (1h)
* install Flash, Java, etc.
* install office suite & other productivity software (1h+)
* rerun Windows Update to catch any new entries due to apps etc. (30min+)
* install anti-malware (antivirus, antispyware, possibly firewall, etc.) (30min)
* lock down, tweak desktop, etc. (30min)
These are all very hand-wavey estimates but very broadly representative, I'd say. Certainly the best part of a day's work. If I got it done in under 4h I'd be very pleased. Under 2h to me would mean a slipshod, incomplete job.
This is excluding any phase of restoring customer data, etc.
Win7 installs a lot more quickly than Vista or XP - that's a boon. Also, Windows Update doesn't need IE, which is also a big win. However, the driver-installation process highlights my single favourite new feature in Vista/W7, which I've never seen highlighted in a review: recursive search through a directory tree for drivers. This is brilliant - this feature alone has saved me days.
With a few exceptions - AMD or nVidia graphics, some wifi chips, touchscreens, some older webcams - most hardware Just Works™ with modern Linux.
With Windows, you'll get some crappy unaccelerated version until you've found the right version of the right driver for the right firmware from your particular hardware vendor, read an EULA, clicked Agree, found a working mirror, downloaded it, unpacked it, found the setup program, run it, installed it, rebooted, and if you're lucky, it worked. And repeated this 26 times, once for each custom chip in the machine.
If it's an older machine, you're screwed; the company won't exist, will exist but will deny the product ever existed, or won't offer a download, and you have to identify the OEM by part number, download an OEM driver from a warez board that wants to give you a !!FREE!! super-helpful malware-infested "driver update tool", and try 6 of them before you find one that works in your country and displays instructions in an alphabet that you can actually read.
So, yes, in my considered opinion, Linux is better at this. OK, your old Winmodem might not work any more, but really, who cares?