Microsoft finally released Windows XP Service Pack 3 (SP3) to the general public, earlier this week, after a minor glitch or two the week before. It is an update that many XP users have been waiting impatiently for, for months.

Despite the fact that it's now available, however, the company still has a caveat for some users. If you have Internet Explorer 7 or 8 already installed, you may want to uninstall it before installing SP3. Then, if you wish, you can reinstall IE afterwards.

Why? As the 1990s buzz phrase goes: it's complicated.

At least that's the message in a posting made on Microsoft's (NASDAQ: MSFT) IE team blog this week.

It revolves around the fact that SP SP2 shipped with IE6. However, XP SP3 ships with a slightly different version of IE6. It also concerns the order in which the service pack and IE7 or IE8 are installed.

"If you choose to install XP SP3, Internet Explorer 7 will remain on your system after the install is complete. Your preferences will be retained. However, you will no longer be able to uninstall IE7," Jane Maliouta, deployment program manager for IE8, said in her blog post. The same goes for IE8, which is currently in beta test.

That's because the uninstallation process saves the wrong set of IE6 files on your hard disk, which would cause big problems later – so you're locked out of simply reverting to IE6.

The best way to handle the problem, Maliouta said, is to first, uninstall IE7, install XP SP3, and then reinstall IE7.

For the more adventurous who may have installed the beta test release of IE8, the warning counts double. Microsoft has set its download sites to not offer SP3 to users who already have IE8 installed – for good reason. If you install SP3 on top of IE8, as with IE7, you will no longer be able to uninstall the beta software.

"Since people are more likely to uninstall beta software, we strongly recommend uninstalling IE8 Beta 1 prior to upgrading to Windows XP SP3 to eliminate any deployment issues and install IE8 Beta 1 after XPSP3 is on your machine," Maliouta added.

Two analysts said they don't view the situation as a significant problem, but one said that it makes the update process more complex than it should be..

"I suppose there could be some applications that are affected, but I don't see it having any impact on most users," Michael Cherry, lead analyst for operating systems at researcher Directions on Microsoft, told InternetNews.com.

Roger Kay, president of analysis firm Endpoint Technologies, was of a similar mind.

"It sounds like a glitch [Microsoft] needs to fix, but it doesn't sound like a big deal," he said. "Still, a user shouldn't have to go through a lot of work to get it fixed," Kay added.

The company had planned to release XP SP3 last week, but that fell through after Microsoft found a clash between the service pack and Microsoft's Dynamics Retail Management System (RMS).

Microsoft announced on Monday it had put a filter in place so that XP SP3 is not offered to users with RMS installed. Then it released the service pack as planned. The company is working to come up with a solution for RMS users.