slow download speeds - Win7 host, XP guest with VPN

[sblack]

So I've done a lot of searching and I have yet to figure out what the problem here is. First up, configuration details:

HOST
ASRock H77 Pro4-M mobo
Intel Celeron G530 2.4Ghz (dual core)
8 Gig 1600Mhz DDR3
Intel EXPI9301CTBLK PCIE NIC card
Win 7 Ultimate (x64)

GUEST
Windows XP
2 gig RAM
Network config - Bridged to Intel NIC - "Intel PRO/1000 MT Desktop (82540EM)" - intel drivers installed on guest

So here's what I'm trying to accomplish here. I want to run my VPN (PIA) inside the guest and leave the VPN off the host so I can run a PLEX server. Everything appears to be setup properly inside the guest. No incorrectly configured devices in device manager.

The problem - The second I start up the VPN on the guest, my DL speed in SABNZBD sits at around 1 MB/sec. The second I turn the VPN off, SABNZBD shoots straight to 3.8 MB/sec (my normal speed). I've tried so many combinations of network settings and can't figure out wtf is going on. I've tried all 6 adapter types (both AMD PCNet, all 3 Intel, and paravirtualized adapter) and nothing. I've tried bridged to my Intel NIC and NAT and no change. Regardless of the setup, the second I pop PIA up, my speeds drop.

However, on the host system, I can pop the VPN on and my download speed doesn't budge - 3.8 MB/sec no problem. The problem only occurs on the guest and only when the VPN is up.

Something else that I can't figure out. I connect on the VPN to "US - East" and on the host, speedtest(dot)net shows me in New Jersey somewhere. However, when I connect on the VPN to "US - East" on the guest, speedtest(dot)net shows me in Britain somewhere. I'm pretty much out of ideas and have exhausted everything I know how to do to alleviate the issue. This is my last resort - can anyone help me figure this out?

Thanks much in advance!

[noteirak]

To me, it looks like the problem is with the VPN software, not with Virtualbox. Do they even support VMs?