I had this problem for a long time.

An error occurred during the installation of the device
Access is denied

When installing my Leadtek Winfast TV 2000 XP deluxe. I had it installed before and had it working, one day I decided to upgrade the drivers, ever since then I get the same error even if I used the old drivers. I tried doing everything, installing new drivers (chipset/video card), upgrading the bios, removing all spyware, looking for viruses with many different AV programs, changing settings in windows, and change the card to a different PCI slot. Here is my PC and information,

AMD XP 2800+
MSI K7N2G-L
Bios 3.7
Chipset Nvidia Nforce 2 IGP NorthBridge MCP2 SouthBridge
Integrated video, audio, and LAN
512mb and a 256mb Corsair pc 2700 Low latency
Seagate 60GB
West 160 gb
ANTEC SOHO Model SX1040BII with 400 Watt Smart Power
LiteOn 52x24x52
DVD-ROM

OS:
Windows XP
SP1

Drivers:
Nforce Chipset 2.45
Video Nvidia 45.23

DirectX 9.0b

IRQ usage:
1,2,3,4,6,8,9,10,12,13,16,20(Nvidia Nforce Audio Codec),20(Standard OpenHCD USB Host Controller),21(Nvidia MCP2 IDE Controller),21(PCI to Host Controller),22(Nvidia MCP network card),22(Standard OpenHCD USB Host Controller) No conflicts listed.

I came up with a lot of windows problems that were very unknown and I easly fixed it. But this one I am stumped.

Please any help would be great,

Are you a member of the Administrators group?

If you mean if I am the administrator on my computer, yes, I am also the only log on name, guest is disabled.

You've probably done all of these, but no sense in not bringing them up.
Generally, the "Access is Denied" warning is given when a file is being used by some system component and you or a process attempts to delete it or overwrite it. Some worms will use .scr files, like brazil.scr, to come up when booting so that they can't be erased. So, look in your startup manager to see what programs are being invoked. You probably won't find a worm, but it will tell you what is being called. You could try disabling the ones you don't recognize and try to install the drivers for the card.
You could try (which you probably already have done) installing through safe mode when certain system drivers are kept to a minimum.
You could uninstall the Nvidia drivers, boot into VGA mode, (erase all the nvidia drivers) install your card, then install the most recent Nvidia drivers.
When all else fails, call Leadtek (which you probably have done) to see if this problem has occured on other machines.

How do I get in startup manger?
I think I am in the right one but its called something else.

Msconfig from run. If you have System Mechanic go to the startup manager.