I want to hear crisp, lossless audio for high-definition video, lossless music and involved gaming. Assuming that I already own an excellent pair of speakers/headphones, would the upgrade from integrated to discrete class not only be noticeable, but also be a reasonable investment?
For most people, the integrated sound is plenty good. If you require audiophile quality sound, then the add-in card will be more suitable. The best strategy is to try the integrated sound, and only if it doesn't meet your expectations, buy the add-in sound card.
The Striker is a solid card, but its hard to not recommend the ASUS Xonar DX over it instead; slightly cheaper and slightly newer model. You have several tiers above that to choose from as well.
The first question to ask is whether or not a headphone amp is a feature that you want/need on a soundcard. That answer changes the recommendation list a bit.
Even going to a mid-tier card like the ASUS Xonar DX, when paired with decent speakers/headphones, is a significant improvement. Going to a top tier card paired with top tier speakers is huge. It really depends how much you want to pay.