Access Windows Boot Manager selector when timeout is set to 0?

I've installed Wubi onto a Windows Vista computer. I've also set the boot timeout to 0:

bcdedit /timeout 0

However, now I can't figure out how to get the menu to come up at all! I read on the internets that I had to hold F8 or space when starting up, but they doesn't seem to do anything. Is there a different key or setting I've overlooked?

The computer itself is a Dell that's a few months old. The keyboard is USB, but I don't think that's the problem as I can get into the BIOS just fine. Maybe I'm doing it wrong? Am I supposed to hold the keys or rapidly tap them (I've tried both)?

If it helps, here's the output from bcdedit:

C:\Windows\system32>bcdedit

Windows Boot Manager
--------------------
identifier              {bootmgr}
device                  partition=C:
description             Windows Boot Manager
locale                  en-US
inherit                 {globalsettings}
default                 {current}
resumeobject            {5460d9d2-d391-11dc-9d9f-aba67a8797c5}
displayorder            {current}
                        {e2484fe7-5e97-11de-84d4-0024e8074422}
toolsdisplayorder       {memdiag}
timeout                 0
resume                  No

Windows Boot Loader
-------------------
identifier              {current}
device                  partition=C:
path                    \Windows\system32\winload.exe
description             Windows Vista
locale                  en-US
inherit                 {bootloadersettings}
recoverysequence        {572bcd55-ffa7-11d9-aae0-0007e994107d}
recoveryenabled         Yes
osdevice                partition=C:
systemroot              \Windows
resumeobject            {5460d9d2-d391-11dc-9d9f-aba67a8797c5}
nx                      OptIn

Real-mode Boot Sector
---------------------
identifier              {e2484fe7-5e97-11de-84d4-0024e8074422}
device                  partition=C:
path                    \ubuntu\winboot\wubildr.mbr
description             Ubuntu