This article describes the differences between Windows XP
Service Pack 1 (SP1) and Service Pack 1a (SP1a). Windows XP updates are
distributed in service packs. You can use service packs to help keep Windows XP
current and to extend and update the functionality of your computer. On
September 9, 2002, Microsoft released Windows XP SP1. On February 3, 2003,
Microsoft released SP1 again as SP1a.
If you are not running Windows XP SP1, install SP1a to make
sure that you have the latest security and reliability updates for Windows XP.
Install any appropriate security updates and hotfixes that are already released
or that will be released after SP1 on Windows XP-based computers that are
running SP1a. Windows Update will continue to offer the same set of updates for
Windows XP-based computers that are running either SP1 or SP1a.
determine if you are running Windows XP SP1, right-click My
, and then click Properties
. If "Service Pack
1" appears under System
, you are already running Windows XP
SP1. There is no benefit to installing SP1a if you are already running Windows
XP SP1. Microsoft does not recommend that you install SP1a if you are already
Windows XP SP1a is the same as Windows XP SP1 except that
the Microsoft virtual machine (VM) is removed in SP1a.
- Windows XP SP1a does not include or install the Microsoft
VM, which provides support for running Java programs.
Note If you are running Windows XP or Windows XP SP1 with the
Microsoft VM, you can continue to update the Microsoft VM by using Windows
Update. If you are running Windows XP without the Microsoft VM, you do not have
to install updates to the Microsoft VM. Therefore, these updates are not
offered to you when you visit Windows Update. Microsoft is no longer able to
provide a download of the Microsoft VM for computers that do not already have
the Microsoft VM installed. For more information, visit the following Microsoft
Web site:To determine if you are running the Microsoft VM, follow these
- Click Start, and then click
- Type cmd, and then click
- At the command prompt, type
jview and then press ENTER.
If you are not
running the Microsoft VM, you receive the following error message:
is not recognized as an internal or external command, operable program or batch
- When you install Windows XP SP1a, the following changes are
made to the registry. These changes indicate that SP1a is installed:
- The title for the Windows XP Service Pack 1 entry in the
Add or Remove Programs tool in Control Panel is changed to "Windows XP Service
- You can use this entry to remove the service pack. It
is present only if you choose to archive files when you install the service
- This entry is not updated if you use the Microsoft
Software Installer package to install Windows XP SP1a.
- The title for the SP1a Release Notes has been changed to
include "SP1a" in most languages. In other places where "Service Pack 1" is
used, the text has not been changed.
Note On the Microsoft Web site, "Service Pack 1" may be used in some
cases to refer to either SP1 or SP1a.
There are no other changes or fixes included in this update.
For additional information about what is fixed in
SP1 and SP1a, and how to obtain SP1a, click the following article number to
view the article in the Microsoft Knowledge Base:
How to Obtain the Latest Windows
XP Service Pack