The generic chinese cables that are compatible with VCDS; will require "VCDS Lite", which is limited in its capabilities (no can bus cars;limited functionality) and without support from Ross Tech. The chinese cables; may or may not come with a hacked/pirated older version fo VCDS but I cannot comment on this, I chose to support the company that gives us such a great product, as VCDS ($300 is a great price; for a pro level scan solution). Read more about the differences; between the full version and the lite version here:
Ross-Tech: VCDS: Function Table
VCDS Lite does not work with CAN BUS models; I'm not certain about the new beetle as the New Beetle seems to have continued to use the older setup:
"The New Beetle continued to use the older k-line diagnostics only incorporating CAN for Generic OBD-2 in 2008 as mandated by the EPA. Other holdover models such as the 7V Seat Alhambra, 6L Seat Ibiza/Cordoba, 6Y/5J Skoda Fabia, 1U Skoda Octavia, 5J Skoda Roomster, 3U Skoda Superb and others may have continued to use the older k-line diagnostics into and past 2008. In doubt, contact Ross-Tech via email."
Ross-Tech: VAG-COM: CAN-Bus Information
So, I would contact Ross Tech but being your car is a 2008; it may not work with VCDS Lite and therefore, not be a option. Conact them; for confirmation. That being said; if you are going to keep the car and want to do repairs yourself, I would get the FULL version of VCDS @ $300 and be fully compatible even to the latest models of VWs now being sold: this would be the HEX-USB+CAN cable and software solution. This is the most affordable and compatible version of VCDS; that Ross Tech sells and you get FULL support from Ross Tech over the phone or through their support forums open only to registered users of VCDS:
HEX-USB+CAN
Ross-Tech: HEX-USB+CAN Interface
Ross-Tech Store: VCDS
I have had the above; since 2007, it has been excellent, has free software upgrades for life and has saved me thousands in repairs, frankly... without it, my car would not be on the road today! Buy it; you won't regret it!
In my case; it paid for itself, the first time I used it! 
Less expensive options:
If you are not ready; to spend the $300, you might buy a basic VW compatible scanner like the Vgate VS450 off of amazon.com for $50. It would provide you with the VW specific scanning of the onboard computers and give you the VW specific trouble codes, to help you diagnose your car and you could clean the codes, as well. According to the description it is CAN BUS compatible; I have not heard of any feedback from users on here with a 2008 model but amazon.com has excellent a generous return policy, if it doesn't work (I don't see why it wouldn't ). Hope this helps; if you have anymore questions, let us know!
Ross-Tech: VCDS: Function Table
VCDS Lite does not work with CAN BUS models; I'm not certain about the new beetle as the New Beetle seems to have continued to use the older setup:
"The New Beetle continued to use the older k-line diagnostics only incorporating CAN for Generic OBD-2 in 2008 as mandated by the EPA. Other holdover models such as the 7V Seat Alhambra, 6L Seat Ibiza/Cordoba, 6Y/5J Skoda Fabia, 1U Skoda Octavia, 5J Skoda Roomster, 3U Skoda Superb and others may have continued to use the older k-line diagnostics into and past 2008. In doubt, contact Ross-Tech via email."
Ross-Tech: VAG-COM: CAN-Bus Information
So, I would contact Ross Tech but being your car is a 2008; it may not work with VCDS Lite and therefore, not be a option. Conact them; for confirmation. That being said; if you are going to keep the car and want to do repairs yourself, I would get the FULL version of VCDS @ $300 and be fully compatible even to the latest models of VWs now being sold: this would be the HEX-USB+CAN cable and software solution. This is the most affordable and compatible version of VCDS; that Ross Tech sells and you get FULL support from Ross Tech over the phone or through their support forums open only to registered users of VCDS:
HEX-USB+CAN
Ross-Tech: HEX-USB+CAN Interface
Ross-Tech Store: VCDS
I have had the above; since 2007, it has been excellent, has free software upgrades for life and has saved me thousands in repairs, frankly... without it, my car would not be on the road today! Buy it; you won't regret it!
Less expensive options:
If you are not ready; to spend the $300, you might buy a basic VW compatible scanner like the Vgate VS450 off of amazon.com for $50. It would provide you with the VW specific scanning of the onboard computers and give you the VW specific trouble codes, to help you diagnose your car and you could clean the codes, as well. According to the description it is CAN BUS compatible; I have not heard of any feedback from users on here with a 2008 model but amazon.com has excellent a generous return policy, if it doesn't work (I don't see why it wouldn't ). Hope this helps; if you have anymore questions, let us know!