The time to get into BIOS

[#1]

When you boot up a pc, it gives you a certain amount of time to indicate (usually by using F2 or DEL) that you want tyo access the BIOs. In my case, my Compaq Evo D500 pc uses F10. Is there a way of adjusting the time that I get to use F10?
The reason I ask is that my Compaq seems to accept the F10, (it changes the message "F10=Setup" to "Setup") but goes straight into Win Xp anyway so I cannot access the BIOS.
Does anyone know how to adjust this time, please?
Thanks

[#2]

There is no way of changing the time. If you have a floppy drive the old trick is to put a none bootable disk in and provided its set to boot from floppy first it gives you more time to catch it

[#3]

Another trick that works on some BIOSs is to hold a key down as soon as you power on or reboot. This will sometimes cause the BIOS to halt with a keyboard error and then a message like 'Key F1 for BIOS or F2 to continue'.
I don't know of any BIOS where you can change to delay to go into Set-up.

[#4]

Thanks both of you for your suggestions. I have now tried the "hold a key down during bootup". That got me into the BIOS, where I went looking for something that might cause this BIOS access problem.
I found under "Advanced/Power-on Options" that "Post Mode" was set to "QuickPOST". I have changed that setting to "FullPOST", and now I can get into BIOS everytime.
Regards and thanks.