Firstly; these are the words of phr; a newbie to the custom ROM scene. He has basically used vmWare on his Vista x64 PC to successfully update his Omnia (yyes, we all know it shuld of been done on an XP machine, well it was, just a vm (virtual machine).

Please read this guide, i have not edited it in anyway, and i will also post in the ROM discussion threads too.

Here goes....

I've successfully flashed my Omnia (which was previously PNHJ1) with this ROM, using Windows Vista Ultimate x64 and VMware Workstation 6 and it works just brilliant!!

If anyone would like to try it this way, here's a little guide

BUT REMEMBER, I TAKE NO RESPONSIBILITY IF U DAMAGE YOUR DEVICE! ..it worked by me 100%.

If you don't know what VMware is, take a look at http://en.wikipedia.org/wiki/VMware for more information.

Things you'll need on vista:
 
 - VMware Workstation (I'm using version 6.5)
 - Microsoft Windows XP CD or .ISO image and the serial key
 - 2gb of free disk space

Things you'll need later on XP:

 - Shokka9's killer ROM (I'm sure it's possible with others too, but didn't tried it)
 - Samsung Modem Driver for XP
 - MS Active Sync
 - Archieve manager.. here's a good, free one.. http://peazip.sourceforge.net/
 - Mozilla Firefox (optional)

Files can be also found here: http://www.4shared.com/dir/11391833/65a43fc0/Samsung_SGH-i900_Omnia.html

Here we go:

First install VMware's Workstation. You can get a trial version at http://www.vmware.com/

If you have an .ISO image of your Windows XP CD on your hard disk like I do, you won't need the CD, otherwise you'll need it. If you don't have the image, put the CD into your CD/DVD-ROM.

Run the workstation.

Go to FILE -> NEW -> VIRTUAL MACHINE and choose TYPICAL. On the next tab select the source from where you want to install a virtual Windows XP operating system (CD or image).

On the next tab, press next. When the dialog appears, choose YES.

Now enter a name for your virtual XP machine and choose a location where you want to save the machine - it's good to have at least 2gb of free space!

On the nex tab, I've chosen 2.5gb. I think that's enough, if you wish only to flash your ROM.
You can choose to install the machine to a single file or splitted. I've chosen single.

On the next tab, click Customize Hardware button and select "USB Controller". Make sure High-Speed USB 2.0 and Auto connect USB devices are checked. Press OK, then press FINISH.

Maybe you'll get a warning from VMware but don't bother, just skip it.

The Windows installation process should follow. The installation took on my PC for about 25min.

When the setup has finished, you can normally run and use Windows XP via WMware.

The first thing I did after install, was downloading and installing Mozilla Firefox, so I could download other stuff without errors from Microsoft's IE. 

Download PeaZip, Active Sync, Samsung Modem Driver and of course shokka9's ROM.

Install the modem driver, PeaZip and Active Sync and reboot your XP.

When back into OS, use PeaZip to extract part1 of the ROM - other parts will be extracted automaticly.

Plug-in your Omnia and make sure Active Sync finds your Omnia.

Take a look for the USB icon at the bottom in VMware. If the icon lights up after you plugged in your device, then everything should be fine. At least it was by me.


After that follow the steps at
http://www.samsung-omnia.org/rom-discussion/how-to-use-a-custom-rom-(xp-only)/ and
http://www.samsung-omnia.org/shokka9%27s-kitchen/**-new-**-dxia5shk15m-**-new-**/

and you should soon flash your own ROM

I hope that was helpful.
Good luck!

Many thanks to shokka, you're a lifesaver! ..and to all others at the community

Many thanks to phr for this excellent guide!!

Just to add, i have tried SUN's virtualbox and Microsofts Virtual PC, cannot work to flash Omnia. virtualbox would not let active sync see the Omnia, and Virtual PC will not do USB anyway.

Enjoy.