First of all when going to plug in any usb device one thing you will find a mandate regardless of which you are running is the need to have the system awake or booted up to the desktop. For hibernation or sleep modes you may even want to click the restart so everything boots up fresh again before plugging the usb device in.
This will allow ffresh detection of the device. If you simply plug a device while hibernating or in sleep it won't be.
Now for boot time I had XP, Vista, and the 7 beta and RC build all installed while testing 7 originally with both the 32bit and 64bit builds set up with the existing XP/Vista(default boot OS then) dual boot and made the comparisons as well as seeing Vista and XP go back onto the previous buid used then and now seeing 7 retail after the old case was passed along to a friend. In every instance 7 arrived at the desktop faster then either of the two previous versions unless there was a problem or severely loaded down with startup.
(When first seeing the retail 7 go on I stressed tested the then brand new version by loading it to the max with sorts of freebies as well as paid for apps in order to push the limits)
Shutting 7 down when powering down is also faster with 7 over the two previous versions with one guide here explaining how to lower the "WaitToKillServices" registry value from the default 20000 in XP and Vista(both seeing the same) and 7 with 12000 as the default. The rec is about 1000 while I run about 800 some lower at 500. A few guides reflect on that while the earliest and first mentions lowering from the 12000 value to 2000.
http://www.sevenforums.com/tutorials/717-shut-down-speed-up.html
The reason for the higher 2000 value there is often you will tend to see the "waiting to close...." when restarting or shuting down 7 when the value is lowered too far. For the novice and not so savay user 1200-2000 is a good value range for that tweak.
Now if you are wondering why 7 is seeing more processes then XP look back one version to Vista which was often labeled the bloated OS until 7 came along when MS realized Windows was getting too big! Many of the newer services involve supports for newer technologies not present back in the 2000-2001 time frame when XP was first being developed. The two newer versions offered more features not seen previously in any of the older NT or Legacy versions.
Up until a certain point XP required a driver floppy or cd burned with sata drivers since the older version was unable to detect any Sata I or Sata II drive when going to install Windows. Vista then saw generic driver support included in the OS until chipsets on the newer boards then allowed XP to see sata drives. Just another point to indicate that XP will only become even more promatic after the support is abandoned for good no longer seeing those extra driver sets and no more SPs to add new support for newer things to come simply being too old even now to be run on a practical day to day basis. Let's face it people it can nostalgia on a VM but as far as trying to use it as the main OS at this late date it's time to give it a good retirement package.