This is copy paste from another site ,the OS's are switched around but the cure should work for you

Give dual boot the boot

Q: I installed Windows XP on a new hard drive in my PC, but I kept the old drive containing Windows 98 SE as my D: drive. Windows XP apparently detected the 98 SE operating system on the old drive and now offers me the choice of dual-booting at start-up. How do I get rid of this option?

A: You'll need to edit the boot menu, which is controlled by the C:\boot.ini file on your Windows NT, 2000, or XP boot drive. This small text file contains various parameters that control the boot-up delay (Timeout=), the default operating system, and information about which drive and partition contain your two operating systems. Your current boot.ini file probably looks similar to this:

[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Home"
D:\="Microsoft Windows 98"

To access the boot.ini file, click Start, right-click My Computer, select Properties > Advanced, then click the Settings button under Startup And Recovery. In the Startup And Recovery dialog, click the Edit button under System Startup. This will open the boot.ini file with Windows' Notepad program.

To open the file without the long string of dialogs (using Notepad or another text editor), you must first remove the file's read-only attribute. To do so, click Start > Run and type cmd. Click OK, and you'll see a command-line dialog. At the command prompt, type CD\, then press Enter. Now type attrib -r -a -s -h boot.ini (note the spaces between command letters and the hyphen for the next letter) and press Enter. This will remove file attributes that would prevent you from editing the file. Next, type notepad boot.ini and press Enter to open and edit the file.

Now, to remove the Windows 98 boot option, simply delete this line: D:\="Microsoft Windows 98." Without the line, Windows XP becomes the default start-up OS. If you prefer to leave the dual-boot feature as is, but you want Windows to start the default operating system sooner, simply replace the number after Timeout= to something less than 30 seconds. (Windows will present you with a dual-boot option, but it will launch XP within the time you specify.) When you have completed your edit, save the file and close Notepad.

I had this same type of prob. your info got me on the right track. I was able to use your info and figure out what I needed to do in my situation. It was a guess, I didn't know if it would work, but I had to try it and it did I thank you for your time and your knowledge. It has been a great privilege Thank You Cyrus

edit the boot.ini file
set default on w98
if that works; set timeout = 0

no screen anymore!

mifa

A while back I tried to install Windows XP on my computer. I was not able to because Windows 98 was already installed. Since then I changed my mind and continued using Windows 98. Now, because I started the install of XP I have this error message whenever the computer starts. It goes to the message "Please select the operating system to start" and if your not quick enough it will go through the whole XP setup thing again. It is quite annoying and would love to get rid of this thing that obviously contains some sort of setup data that stays on my computer. can anyone help me to REMOVE the setup data so I can just boot right to Windows 98 like I use to? Thank you very much!