Any linux distro with the codecs, plugins etc pre-installed will be dependent upon bug testing on different architectures and different systems (32 bit, 64 bit, laptop, dual core, etc.). The more testers out there the better the likelihood that your particular system is bug free. Unless you're willing to install packages to a base system, you'll just have to try different distros until one works out best for your particular system. I've had my best success with Mepis, but primarily have used HP laptops and desktops over the years. You may want to post your particular system, and then ask the forum who has had out-of-the-box success for the same system.

As you can see there are as many different opinions about which distro is most complete out of the box as there are respondents to your question. The beauty of Linux is that they are all correct from their own point of view. Testing and experience and personal preference all lead to well reasoned answers. You can arrive at your own best answer.
I would respectfully direct you to DISTROWATCH.COM to begin your research.
On the distrowatch home page, scroll down the right side to the Hits Per Day (HPD) listing to get a feel for the distributions that have attracted attention. That's not to say which is best for you, but to give you a place to start. Click on any that interest you and read the descriptions. Then note the individual programs that are included with each by default.
You will soon get a feel for how well they meet your specific needs and/or desires. Each can be downloaded or purchased via the links on the page.

My own preference has narrowed down to KUBUNTU 13.10 and MINT 16. I like the KDE desktop of KUBUNTU and I like the look and ease of installation of MINT. Plus I have never found anything lacking from either one.

This thread originated in 2008 probably the Original Poster figured that out by now.

After 8+ years with Linux, this is my (humble) opinion: Linux is ALWAYS a learning and experimentation process. If this does not sound interesting and like fun to you, well, Linux can still accomodate you. In my opinion do NOT start with a distro that requires you to configure everything, such as Debian, Arch and many others, they are all great distros, for LATER.
Step 1: Start with Linux Mint, probably the 64 bit (depends on your machine) Mate desktop. Why? lots of users, good forum, your questions are all documented, just google your question, you WILL find the answer easily. This is your stable new platform, not too much experimantation there. Are you happy, probably, leave well enough alone.
This does not mean that there are no other distros that will give you excellent results, but this is a tried and proven to work approach.
Now you work with it, and get all the things working, webcam, printer, skype etc.

Step2: For the ones that try to do the same with different distros: install the Linux Mint Debian version, LMDE. Same approach, get everything working, get the terminology, the issues, the principle, resolve all issues.
Put the home directory on a separate partition, learn how to install a different linux version, mount your existing home partition and so forth.
Step3: Debian is a platform that has become a standard worldwide. Go and install wheezy! Now you are really hooked, Linux will never cease to interest you now.

Happy long nights, with toothpicks in your eyelids.