Black Magic Capture Card problem?

-hi i want to buy a capture card i have a

The Acer Aspire AS5742G Laptop has a screen size of 15.6 inch and is powered by an Intel Core 2.53 GHz i5 M460 Processor. This laptop has

Nvidia GeForce GT420M graphics a 500 GB HDD and 4GB RAM.

This Laptop comes bundled with Windows 7 Home Premium (64-bit) operating system.



i was wondering which one i should by because i have no clue which to buy because i dont want to spend that much money for it not to work. please help here it is.

please tell me what i need to run them thx





http://www.blackmagic-design.com/products/