Most Windows 7 reviews have focused on its interface changes: new taskbar, streamlined start menu, larger preview thumbnails, and so on. But that's just the start.

Had you noticed that it's now possible to defrag multiple drives in parallel, for instance? Discover which IE add-ons take the longest to load? Automatically reduce the volume of your speakers when making a VoIP call?

We have: here's what you need to know.

Note: this is the fourth part of our regular series of Windows 7 tips, tricks and hacks. Check out part one, part two and part three for more tips.

1. Speedy defrags
The standard Windows 7 defragger offers a little more control than we saw in Vista, and the command line version also has some interesting new features. The /r switch will defrag multiple drives in parallel, for instance (they'll obviously need to be physically separate drives for this to be useful). The /h switch runs the defrag at a higher than normal priority, and the /u switch provides regular progress reports so you can see exactly what's going on. Enter the command

defrag /c /h /u /r

in a command window to speedily defrag a system with multiple drives, or enter defrag /? to view the new options for yourself.

2. Load IE faster
Some Internet Explorer add-ons can take a while to start, dragging down the browser's performance, but at least IE8 can now point a finger at the worst resource hogs. Click Tools > Manage Add-ons, check the Load Time in the right-hand column, and you'll immediately see which browser extensions are slowing you down.

3. Fix the taskbar
Windows 7 has tightened up its security by refusing to run gadgets if UAC has been turned off, so limiting the damage malicious unsigned gadgets can do to your system. If you've disabled UAC, miss your gadgets and are happy to accept the security risk, though, there's an easy Registry way to get everything back to normal. Run REGEDIT, go to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Sidebar\Settings, create a new DWORD value called AllowElevatedProcess and set it to 1. Your gadgets should start working again right away.

4. An Alt+Tab alternative
You want to access one of the five Explorer windows you have open, but there are so many other programs running that Alt+Tab makes it hard to pick out what you need. The solution? Hold down the Ctrl key while you click on the Explorer icon. Windows 7 will then cycle through the Explorer windows only, a much quicker way to locate the right one. (And of course this works with any application that has multiple windows open.)

5. Disable smart window arrangement
Windows 7 features interesting new ways to intelligently arrange your windows, so that (for example) if you drag a window to the top of the screen then it will maximise. We like the new system, but if you find it distracting then it's easily disabled. Run REGEDIT, go to HKEY_CURRENT_USER\Control Panel\Desktop, set WindowArrangementActive to 0, reboot, and your windows will behave just as they always did.

6. Tweak System Restore
There was very little you could do to configure System Restore in Vista, but Windows 7 improves the situation with a couple of useful setup options.

Click the Start orb, right-click Computer and select Properties > System Protection > Configure, and set the Max Usage value to a size that suits your needs (larger to hold more restore points, smaller to save disk space).

And if you don't need System Restore to save Windows settings then choose the "Only restore previous versions of files" option. Windows 7 won't back up your Registry, which means you'll squeeze more restore points and file backups into the available disk space. System Restore is much less likely to get an unbootable PC working again, though, so use this trick at your own risk.