These are some of the troubleshooting steps that you can try to resolve your issue.
I suggest you download and run the installer cleanup tool on your laptop. Here a link to the tool. http://support.microsoft.com/kb/290301
Remove if service pack is listed and then try to install it.
To boot your computer into safe mode refer the steps given below:
1. Remove all floppy disks, CDs, and DVDs from your computer, and then restart your computer.
Click the Start button Picture of Start button, click the arrow next to the Lock button Picture of Lock button, and then click Restart.
2. Do one of the following:
If your computer has a single operating system installed, press and hold the F8 key as your computer restarts. You need to press F8 before the Windows logo appears. If the Windows logo appears, you will need to try again by waiting until the Windows logon
prompt appears, and then shutting down and restarting your computer.
If your computer has more than one operating system, use the arrow keys to highlight the operating system you want to start in safe mode, and then press F8.
3. On the Advanced Boot Options screen, use the arrow keys to highlight the safe mode option you want, and then press ENTER. For more information about options, see Advanced startup options (including safe mode).
4. Log on to your computer with a user account that has administrator rights.
Run SFC scan before and then try to install service pack 1.
1. Click Start, click All Programs, click Accessories, right-click Command Prompt, and select Run as Administrator.
2. Click Continue or supply Administrator credentials if prompted.
3. In the Command Prompt window type the following, and press Enter:
4.You should see the following on-screen messages:
Beginning the system scan. This process will take some time.
Beginning verification phase of system scan.
Verification % complete.
5. Once the scan has completed you will receive an onscreen message resembling one of the following:
…found no integrity violations
…found corruption but repaired it
…found corruption that it could not repair
6. Please reply with the completion message that you received.