UPDATE: This offer is no longer available.

If you're a fan of flying Southwest, you're probably also a fan of their easy-to-understand frequent flyer program— Rapid Rewards. Fly 8 roundtrips anywhere, and get one roundtrip free. Couldn't have been much more simple than that!

Unfortunately, as of March 1st 2011, Southwest's frequent flier program just got a lot more complicated. The major change is that they will now issue points instead of credits, and your points will have different values depending upon what type of fare you choose for your award.

I'm not a big-time Southwest flier, but I think it's safe to say that a lot of their customers won't be happy with this change. I've had several friends already talk about getting rid of their Southwest Rapid Rewards credit cards since they are moving to a new points-based system too. What I've been telling them is that if you're looking for a new airline rewards credit card, you should really check out this huge promotion that Capital One is starting today for its Capital One Venture Rewards card.

This might be the first time you hear about the new offer, but it certainly won't be the last. Capital One is pulling out the big guns and promoting this with the help of Alec Baldwin, whose cheesy grin you'll likely see plastered all over your TV, the web, and billboards in the coming months. All media hype aside, I think this really is a great deal from Capital One.

Here's why:

The Capital One Venture Rewards card will match 100,000 miles from another airline rewards card after you meet their spending threshold during the first 3 months.  So how do you get your 100,000 in miles matched? It's really pretty simple.

Let's say you have a United Mileage Plus card with 100,000 miles. To get your match from Capital One, you would need to submit your airline rewards statement to Capital One and meet the spending requirement during the first 3 months ($1,000 in purchases). Then voila—your new Capital One Venture card will get 100,000 miles plus a 10,000 mile bonus. 

Nothing happens at all to the 100,000 miles from your United Account. They remain untouched. The fact that Cap One is also waiving the $59 annual fee for the first year really makes this a no brainer. It's at least worth trying out, which is why I'll be applying for my Capital One Venture Rewards card this month too.

While the promotion is set to run from March 9th through May 13th, Capital One plans to pull the plug when they match a total of 1 billion miles. Who knows how fast that'll happen, so I wouldn't wait around too long if you're still sitting on the fence.