5) Control Your Trash
By default, both the Recycle Bin and Internet Explorer's Cache want to consume ridiculous amounts of your hard drive space. Right click on the Recycle Bin, select Properties, and on the Global tab, decide how much space you want the Recycle Bin to consume, either for all drives in your system, or on a per-drive basis. (It's a percentage of the total space. I adjust the slider way to the left, so I'm using "only" a few hundred megs of space for trash.)

Similarly, open Internet Explorer, and select Tools/Internet Options. Under Temporary Internet Files, click the Settings button and select a reasonable size for this cache area. Generally speaking, if you have a fast connection, 5 Mbytes to 10 Mbytes is adequate; 25 Mbytes or so is usually enough with a slower dial-up connection.

6) Rein In System Restore
Like the items in No. 5, above, System Restore is an incredible space hog. It might be worth it, if System Restore were a truly complete and foolproof form of backup, but it's not. At best, System Restore can and will get the core operating system running again after a bad crash, but it doesn't return all files to the pre-trouble state, and it can't remove all traces of a program that went bad. As a result, System Restore's usefulness is limited, and so should be its appetite for disk space.

Right click on My Computer, select Properties, and select the System Restore tab. Select your main drive (usually C:), click Settings, and move the slider to reserve a reasonable amount of disk space. With a good regimen of daily backups, you can even move the slider all the way to the left. (I do.)

If you have more than one drive, you may wish to turn off System Restore entirely for non-system drives. There's little, if any, benefit to be gained by having them monitored. And if you're really religious about making a full backup before you alter your system or install new software, you may wish to completely turn off System Restore for all drives.

7) Improve XP's Virtual Memory Settings
On its own, Windows places your "swapfile" or "paging file" (a portion of your hard drive that's used as a kind of pseudo-RAM) on your C: drive, and sets it up so it can grow and shrink as needed. However, you may be able to do better. For example, if you have more than one physical disk in your system, you may get better performance from either placing the swapfile on the lesser-used disk (assuming it's the same speed as the primary disk) or by splitting the swapfile across two disks. You also may see modest improvements in responsiveness if you set the swapfile to a fixed size, so Windows won't waste time growing and shrinking the file on demand.

Swapfile management has been somewhat of a black art in previous versions of Windows, but the XP Help System actually has good information on the subject (a first for Windows!). Select Help And Support from the Start menu, and do a search for "virtual memory." Be sure to check out the "related topics" delivered by the search for additional good information.

8) Control XP's Hidden Devices
For reasons known only to the programmers in Redmond, XP may deliberately hide certain system devices from you. While this might make a kind of sense in, say, XP Home edition, these devices remain hidden even in the Professional edition.

For example, if you're used to Windows 98's networking applet, you may be surprised by how clean and uncluttered XP's networking applet is. But XP may simply be hiding lots of networking elements from you. To see if this is the case, right click on My Computer, select Properties, Hardware, and Device Manager. In Device Manager, select View and Show Hidden Devices.

Depending on how XP was set up, you may find a number of networking devices--"Miniports"--that the Networking applet didn't display. In my case, I found unnecessary PPOE, PPTP, L2TP, and Dial Out elements. I disabled all these unneeded elements, leaving only the IP miniport enabled, and thus restored some sense of control over my networking setup. Depending on how your system is set up, you may find other hidden devices, or no others. It varies hugely. But at least now you'll know if XP is hiding things from you.

9) Take The Brakes Off Your Network Settings
XP's default network settings for Maximum Transmission Unit, Receive Window, and such, may or may not be ideal for your circumstances. The only way to know is to take a close look: For example, DSL Reports and SpeedGuide have excellent free information, online tests, and even one-click tweaks that can automatically optimize all or some of XP's internal plumbing for high-speed connectivity. DSL Reports also offers a free, simple network tweaking tool called DrTCP that lets you instantly and easily adjust a variety of parameters; this tool makes iterative testing a snap, as you experiment to find the best settings for your particular setup.

(Incidentally, when WinXP-specific solutions aren't offered, use those for Windows 2000; that's the closest match for XP.)