I would like to perhaps correct the above answer that was marked 'Correct'. I know it's 4 years later but I was going nuts trying to get this to work and I finally did. I bought a $10 1GB USB LAN adapter that has the Realtek RTL8153 chipset in it.
This does support 802.1q MULTIPLE VLAN tagging/trunking with the Realtek supplied Windows drivers. I have a Cisco 2960 switch and I setup one of the switchports for trunking and I allowed VLAN's 10, 142,192 and 250 on that Cisco trunk port. You can allow whatever you want. Then I ran a CAT-5 cable from there to the USB LAN adapter and set it up for those 4 VLANS. When you install the Realtek drivers, you will see the USB LAN adapter as a single entity in Windows. When you then use the Realtek 'Diagnostic' software and create your individual VLAN's, that will in turn create an additional adapter per VLAN in Windows.
So I created 4 VLANS's and I have 5 adapters, 1 is the TRUNK and the other 4 are for each VLAN. Then you go into each of the 4 and set your TCP/IP settings, as the main adapter is now a trunk and has nothing to do with the TCP/IP stack. Now my laptop has 4 separate IP addresses, but remember, you can only have the one main default gateway provisioned, like on whatever VLAN adapter your connecting to the internet. If you wanna push traffic out of one of the VLAN adapters that is not part of that subnet, then setup some Windows persistent routes to do so for that.
I set this up on 2 laptops, one is Win-7 32 bit and one is Win-7 64 bit. I had the most problem with the 32 bit one. So this is what I used and I know it works. On the 64 bit I loaded the Realtek driver package version 7.21.1019.2015, which I had laying around. Then I loaded the Realtek Ethernet Diagnostic Utility version 188.8.131.52. Realtek has this stuff on their website. I took the one made for my chipset, the RTL8153. Once all that was loaded on the 64 bit machine, it was easy to get into the Diag utility and create the VLAN's.
After you create a VLAN, it takes time for it to build that adapter and place it as an adapter in Windows networking. For you to know its going to work, after you create your VLAN, you MUST see a MAC address populate in that create box in the Diag utility. This is where things were NOT happening for me in my Win-7 32 bit machine. It would create the VLAN, it would place the new adapter in Windows but there would NOT be a MAC address in the adapter box and there would be a red X in the adapter in Windows. This is where a lot of people are having problems. That big red X, even though you have a LAN cable plugged into the adapter. This is ALSO where I believe the original poster here had problems when he couldn't add VLANS In the Diag utility, even though you know you have the Realtek chipset that supports it.
How I fixed this was to go into the main adapter in Windows and UNCHECK every box and only have 3 boxes checked, which are 'QoS Packet Scheduler', 'Realtek Vlan Protocol Driver (NDIS 6.2)' and 'Realtek NDIS Protocol Driver (NDIS 6.0)'. Then when I saved and exited and went back to the Diag utility, I was able to create the VLAN's and see the MAC addresses. In Win-7 32bit, is was the 'Deterministic Network Enhancer' that was the culprit. When I unchecked that on the main trunk adapter, then the extra menus appeared in the Diag utility to create the VLAN's.
Hopefully this may help someone get through setting up theirs. I was tired of having 4 separate USB LAN adapters and the main built in LAN adapter in my laptop, so I consolidated to a single trunk LAN adapter. Some my ask what's the need for all this? I have Cisco lab and I remote desktop into this one laptop and I control many things in my lab on 4 different subnets from one machine. That's my need.