As you know, the BIOS on your PE T100 does not allow your to disable the integrated ATI ES1000 video controller which means you will run into all sorts of issues. And no doubt you have seen the many posts on such topics with the many hit/miss outcomes.  In another posts you asked about removing the management card (which in some systems is a pci card laid flat on the motherboard and contains the ES1000 graphics amongst other functions). But there is no mention of such a card on the T100 hardware owners manual so it doesn't seem to have one to remove. And the odd thing in the HOM is that on page 106 we see, "Trouble Shooting Video Subsystem,Action 2. Determine whether the system has an expansion card with a video output connector. In this system configuration, the monitor cable should normally be connected to the connector on the expansion card, not the system's integrated video connector. To verify that the monitor is connected to the correct video connector, turn off the system and wait for 1 minute, then connect the monitor to the other video connector and turn the system on again". Hardly a statement that clarifies much! I would expect that if the BIOS actually does not allow one to disable the integrated video, then there should be a clear statement that video expansion cards are not supported and that the system's integrated video connector should always be used.  My only suggestion is to try the NVS300 in the x8 PCIe slot and if that fails, try a cheap ATI based x16 PCIe consumer card of similar vintage to the ES1000 (but this would require cutting a slot on the card's connector to allow it to fit into the x8 slot). Again this may still have conflicts and fail to work so it's a suck it and see approach. A second hand ATI x16 PCIe card can be had for very little outlay (but always test it works in a desktop PC before your start to hack away). 
After working nights and nights on this I have came to the conclusion that the nvidia's apparently have problems with black screening after windows logo.  This is very frustrating but I would really like some help.  I want to get the Pci Express x1 NVS 300 video card to work in my T100 with Windows 7 x64 installed.  I installed the supplied driver and after restart it goes black after windows booting logo. I reboot into safemode and the video is working. I installed the latest NVidia drivers released in Feb 2012. I restart and it goes black. I go back into safemode and made sure windows aero features where off (they already were). I try a bunch more older version from Nvidia and it goes black. I switched a few irq's around in the bios and it goes black. I have no idea what these drivers are doing that causes a black screen but I can not figure it out. I have searched google a ton and a lot of things I tried came from reading other forum posts so I am hoping a Dell guy/gal will step in on this forum.  I have tried it with the vga adapter on my dell lcd monitor and the dvi adapter on my dell lcd monitor. I actually have two slightly different dell lcd monitors and both them have the same issue. I have the card in my pcix 1 slot and that is the only card installed on the motherboard. I have also tried the card in the x4 slot and it comes up but Windows marks it as having a hardware issue and disables the driver.  I just updated my bios to the newest one suggest on my Dell T100 support page which is PET100-010401C and that did not fix anything. Can someone help me?
PowerEdge T100 with new Pci Express x1 Nvidia NVS 300 goes black after windows 
logo!