This is not much a question but some tips I got recently, and hope they will help those who have the same problem.
I put my DVD drive aside for a long time now, since Windows vista can be installed via a usb storage officially. (You can find every where how to boot vista/7 installation from usb drives)
I did the usb booting stuff quite some times on various motherboards, and found the startup speed varies. Particularly, the speed varies at the step when the screen displaying "windows is loading files". The progress bar can run for 3minutes on some MBs, and 20-30 secs on others.
The MBs are all relatively new, all have EHCI (USB2) support, and ECHI option on in the bios setup.
I looked the issue up with google for a long time. Some hints there on the web suggest that the USB2 support when booting a system depends on the ability of BIOS. Before the OS takes full control of devices, a bios service (INT 13H, if I'm not mistaking) equips "boot loader/ealier stage of OS" with the ability of accessing disks.
A bios vendor may disable the USB 2 support in INT13H routine, out of the consideration of compatibility, cost or something else. Of course the USB 2 controllers are there but effects only after the OS fit a appropriate driver for them.
Apperantly some of my (or my friends') MBs fall into that list. It bothers me a little.
I thought my best chance to get the speed right will be a hooking into INT 13H, and get the USB access part correct. There are some DOS drivers do that, as I know, USBASPI.sys is an example. But I need a boot loader to chainload windows installation files after the DOS driver loaded. Grub4dos seems the right tool for me, for it can be started in DOS and it can chainload windows.
But some guys said on the web that it won't work: once the grub4dos.exe is started, the bios service will be reset, and the DOS driver won't be available there.
When investigating grub4dos, I came across another boot loader called plop boot manager, which is relatively simple, with USB 2.0 READONLY support (I guess it hooked the original INT 13H).
To install plop on a USB HD looks hard to me. And it seems plop can chainload only diskes (instead of kernel/bootmgr images, like grub does). I have to use grub4dos as the initial loader on the USB disk.
There should be 2 items customized in the grub menu, the first 1 is to load vista/7 bootmgr, which is located on the usb disk togather with all the content of windows installation disk. The other item is to load plop boot manager.
When grub loads up at the first time, I choose plop boot manager (the 2nd grub item), and plop is up, the INT 13H service is hooked I believe. Then I choose "USB" in the plop menu, to chainload the usb disk. The grub menu shows again, but this time some changes happened underneath: the INT 13H is replaced. Then I choose the item 1 in grub menu, vista/7 installation starts, and the "loading files" progress bar goes as fast as running on the "good" MBs.
The plop job can be automated by configuration, which means you don't have to choose "USB" in the plop menu. But it looks to me the grub menu must be choosed manully, if you want all the loaders/installation files on one disk.
It is also said that plop can work as "USB driver" to grub4dos, by setting INT19H on (returning to grub with INT19H instead of chainloading). I tried but the machine freeze at the plop interface.
There are two other limits to plop: it works on one USB storage at a time only, you can not indicate one when booting device with it. And the USB disk must be plugged on the MB (root hub) directly. A external hub may cause problem. At least it did on my machine.
Other thoughts: It will be nice if grub can get a built in USB driver, to save us some trouble setting up the boot loaders.
The usage of grub4dos and plop can be easily learned on the web. And my USB disk has the id of (hd0) in grub for both loadups.
Thanks for sharing! Why not edit your post a bit, to make it more readable, and maybe we can move it to the Windows 7 section for more users to see?
Thanks, I will try to refine the post by and by. In fact I am not a native english speaker and organize words badly even in my own language. The fact that I work in computer software probably made it worse, for I assume the reader know bootloaders, such as grub, well.