Pre-installed Win7 x64 boot to ramdisk via iPXE

[Robbin]

Hi all
I need to boot a pre installed and pre configured windows 7 via network in ramdisk. The goal is to run graphical application, that heavily uses network.
iSCSI and AOE are not variant, because the system should not rely on network HD, all necessary data should be loaded in RAM.
Windows PE is not a variant because it does not support DirectX, and I even dont know if all needed software can be pre-configured (eg Nvidia driver's configuration).

All the info that I could find describes booting WinPE, WES7 Installation (I need already installed system), or variants with iscsi or aoe.

Is it possible to do what I need with iPXE? And what tools may I need?
Current scheme that I understand is:
client->PXE->DHCP->TFTP->iPXE->wimboot->HTTP->system image->ramdisk->boot up

Things that I cant understand are:
1. Is it possible at all?
2. Use .wim or .iso?
3. Is it possible to put installed system to .wim or .iso?

Thanks for your support