Windows 7 - Works on one computer, but not the other...

I installed the new Windows 7 operating system on my laptop, which previously had Windows Vista installed... Here are the specs:

Gateway - Intel Core Duo CPU
32-bit Operating System
T2250 @ 1.73 GHZ
1GB RAM
128 Integrated Video Memory
100 GB Hard Drive

I downloaded the .iso file, burned it with Nero, and it installed flawlessly...

So then I try to install on my desktop... not so much luck...

Here are the specs:

Dell 4400 - Pentium 4
32-bit Operating System
1.8 GHZ
1 GB RAM
Geforce 7600GS - 512MB Video Memory
130 GB Hard Drive

When I try to install, I get an error in the beginning after the initial web update, every single time...

It says something about not having all the files available for installation? How is that possilible if I can succesfully install it on my other system? Any help is GREATLY appreciated.

I am also installing the CD on an external DVD/RW drive, since this old PC does not have a DVD drive installed. It also does not support USB 2.0. (1.0 only)

By the way, Windows 7 on my laptop has been running great! But my PC used to run 100 times faster with Windows XP. Is there any way I can get my PC running with Windows 7 just like my laptop, and even faster like before?

Any and ALL help is greatly appreciated. Thank you!

Uncheck the check for updates when installing and see if that makes it install.

When I go the "Don't check for internet updates" route, it gives me the error right away, opposed to the 20 second wait going the other way, while waiting on the "Please Wait..." screen.

Let me add, the laptop that it worked on, had Vista installed months earlier...

The PC that it did not work on, had a fresh newly partioned version of XP installed today...

(By the way, I am trying to rewrite over the XP operating system with the 7 system)

this is much faster then vista as far as i can tell, im happy so far

do you have any usb devices pluged-in??
unplug anything unnecessary to the install....

the DVD/RW player is connected through a usb (external), becuase the dell pc is too old it only has a cd/rw and another cd player on it, can I not install through an external dvd player/writer?

Are you starting the install from within windows or from a cold boot?

i have to do it in windows, i can't get it to boot from a restart
i set the boot to the cdrom
then a set the cdrom to start the dvd/rw as primary
and nothing happens

What I would try is mounting the ISO with daemon tools (or other mounting software) and install without using the disk.