Goal:
I want to run a Debian-squeeze-Guest in VirtualBox and it's own public static ip. I found tons of threads about this topic, but all in all I'm now trying for 10 hours (reading the manual, the forums, trying to learn about networking concepts & commands) to give a Guest his own public static ip (so that the Guest is similar to a vServer you can order from a hosting company), but wasn't able to.

Since I'm a big noob as far as networking stuff is concerned, I'm probably doing something wrong.(please bear with me :-) )

Situation:
VirtualBox 4.0.10 (headless no gui) is running on a dedicated Debian-Server, the Guest OS is Debian as well.

The server has a static ip and I ordered an additional ip for a VM.

Problem description:
Upto now I was able to use NAT to access the VM from the outside and to setup an internal network between several Guests and all of this worked very well.

When setting NIC 1 to bridged and configuring a public static ip on the guest, the guest was unpingable. (neither from outside, nor from the host) I could connect to the guest via the internal network, from another vm, though. ( VBoxManage controlvm VMGuest nic1 bridged eth0 ) ( configuration attempt of static-ip on the guest '/etc/network/interfaces' is below)

Please let me know what I'm doing wrong, or what I can try to get it to work, or if you need more info.

I think I've read that with a current VirtualBox-version for bridged networking no special host-configuration is necessary, is that accurate, or might that be the problem?

Additional Info
Info I got from the hosting company about the additional IP

  Please note that you can use the IP address only for this server.

  IP: 46.4.xx.xx
  Gateway: 46.4.xx.xx
  Mask: 255.255.255.248 

VBoxManage showvminfo VMGuest |less

 ...
NIC 1:           MAC: 080027D72F7B, Attachment: Bridged Interface 'eth0', Cable connected: on, Trace: off (file: none), Type: 82540EM, Reported speed: 0 Mbps, Boot priority: 0
NIC 2:           MAC: 080027B03B75, Attachment: Internal Network 'InternalNet1', Cable connected: on, Trace: off (file: none), Type: Am79C973, Reported speed: 0 Mbps, Boot priority: 0
NIC 3:           disabled
(...rest is disabled) 

cat /etc/network/interfaces on the Host-machine

 # Loopback device:
auto lo
iface lo inet loopback

# device: eth0
auto  eth0
iface eth0 inet static
  address   46.4.xx.xx
  broadcast 46.4.xx.xx
  netmask   255.255.255.224
  gateway   46.4.xx.xx
  post-up mii-tool -F 100baseTx-FD eth0

# default route to access subnet
up route add -net 46.4.xx.xx netmask 255.255.255.224 gw 46.4.xx.xx eth0 

cat /etc/network/interfaces on the Guest-VM

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
allow-hotplug eth0
auto  eth0
iface eth0 inet static
  address 46.4.xx.xx
  netmask 255.255.255.248
  gateway 46.4.xx.xx

auto eth1
iface eth1 inet dhcp

ifconfig -a on the Guest shows the correct static ip for eth0 but the Guest is unreachable "over eth0"

eth0      Link encap:Ethernet  HWaddr 08:00:27:d7:2f:7b
          inet addr:46.4.xx.xx  Bcast:46.4.xx.xx  Mask:255.255.255.248
          inet6 addr: fe80::a00:27ff:fed7:2f7b/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:21 errors:0 dropped:0 overruns:0 frame:0
          TX packets:69 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:1260 (1.2 KiB)  TX bytes:3114 (3.0 KiB)

eth1      Link encap:Ethernet  HWaddr 08:00:27:b0:3b:75
          inet addr:192.168.10.3  Bcast:192.168.10.255  Mask:255.255.255.0
          inet6 addr: fe80::a00:27ff:feb0:3b75/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:142 errors:0 dropped:0 overruns:0 frame:0
          TX packets:92 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:15962 (15.5 KiB)  TX bytes:14540 (14.1 KiB)
          Interrupt:16 Base address:0xd240

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:123 errors:0 dropped:0 overruns:0 frame:0
          TX packets:123 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:25156 (24.5 KiB)  TX bytes:25156 (24.5 KiB)