Hello Stefan
I recommend a soundcard which is developed for producing music. So there are several companies which are offering products from cheap to expensive.
"Soundblaster" is more for the general Media-Area - I believe.
Some companies: M-Audio, Presonus, RME, Apogee, Alesis, Roland, ESI, E-Mu, Focusrite and also Tascam of course.
Further:
The interface should support ASIO 2.0 in any case
The interface should come with WIN-7 Drivers in your case. Check this for the desired Interfaces.
Check also whether there are WIN7 64Bit drivers or not. Maybe within 2-3 years most of the music software runs under 64-Bit.
It's not bad to have more than two Outputs which can be used in the meantime (and perhaps Inputs)
It's not bad to have a digital In/Out (S/PDIF)
USB- and Fire- Interfaces are not as fast as PCI(e) cards are.
Nevertheless, USB-Interfaces are often portable and can be handled very easy. But, because of the slow USB-Bus they generate longer latency times.
You know it from your Tascam 144
One of the fastest USB-Interface offers RME
Best
Beat