The Dell computers are very nice, I'm sure it will do everything you would like it to do. From what I've been reading from other posts on this site DO NOT get the Dell proprietary video system. I've heard nothing but problems from this card and just about everyone ends up throwing out that card and buying a different one. They can never get it to work properly and spend hours with tech support, with still no help. I would take Gary's suggestion and go with Pinnacle Studio Deluxe or I would just purchase a Pyro Firewire card, it seems to be the card that works for everyone and has the least problems. To install the card you just have to take off the case and pop it into a free PCI slot, put the case back on and your ready to go. It is honestly really easy and there is good documentation on how to do it, although I doubt you'll even need it. The choice is yours about what video card is right for you but I heavily advise you to stay away from the dell video system. Good luck with your computer and if you have any other questions feel free to ask!
The Dell Movie Studio Essentials looks like it is just a fire wire card with some software.
The Dell Movie Studio Plus is a fire wire card with and added analog capture device. That device has been the subject of several posts in this forum by dissatisfied users. Whether or not those posts are typical of that device's users is another question.
CompUSA and Best Buy carry the Pinnacle Studio Deluxe and will install it for you.
If you choose to go with the Dell Movie Studio Essentials (or another fire wire card for that matter), you have the option of using one of the analog-to-DV converters, such as the Dazzle Hollywood DV Bridge or the Canopus ADVC-100. Installing one is just a matter of plugging it in to the fire wire card plug.