VMware workstation actually works
after about long hours of fighting here are hints :
how to :
* Download and install VMware workstation (vmplayer might work, didn't try)
* Set up a VM, my working VM uses 6.55 GB with a copy of rappelz
* Get a s/n for it, yeah the 30d trial refuses to run the VM !
* Install your XP on the VM
* Not sure if it is necessary but i added : SP1 ; SP3
* Dx march 09 (this is necessary)
* Run Dxdiag and see that D3D is disabled (can skip this step !)
* Alter your .vmx to add mks.enable3d = TRUE and svga.vramSize = 134217728 at the end of the file. this enables D3D support
Now starts the hard part : network configuration
* Check out your firewall for bridge/nat denial (KPF free needs to be turned off when you run the game, you can turn it on again when logged in)
* If you use hamachi or something similar, make sure the host searches the true NIC first (in connexion > advanced menu > advanced > order)
I was able to check buddies PCs via hamachi but not google

* Both NAT or bridge works for me, went for bridge
* The allmighty window is the "Virtual Network Editor" in the edit menu of the VM workstation, there you can configure your networks
* I have desactivated VMnet1 and host-only on the host which are not necessary
note : I have not tried sharing the rappelz folder, i'll try that some day, it might shrink the VM size needed
Of course if you have an easier method that does not involves virtualizing, i'm interessed !
Now it should work ! you can now dual box
I think i have not forgotten anything ...
Enjoy