help purchasing a firewire card and external harddrive [closed]

The ASUS motherboard does not make any difference. Newegg is a good place to get this, particularly if you are unsure what to get. You can sort the filter/search results by customer recommendations. I strongly suggest you use the recommendations as the typical Newegg shopper is pretty savvy. As far as the difference in hard drive prices, size (2.5 v. 3.5) will make a difference, especially in the capacity you're looking at. Also the enclosure is a factor in the price. Again, reading the recommendations is probably your best guide. I expect any card you find that is XP compliant will also work with Windows 7, but read the descriptions.