Truly successful investing means taking a long-term approach. No, that doesn't mean weeks or months. It means years and decades.

In an effort to help force myself to take such an approach, I publicly picked 10 companies last summer that I would be investing more than $40,000 in. I vowed to hold these 10 companies for at least three years, or else make a donation to charity if I sold too soon.

It's been about 11 months since I made that first purchase. Below, you'll see how the portfolio is performing, why it's doing so well, and three companies I think are great buys right now. Read all the way to the end, and I'll give you access to a report on the three stocks that'll help you retire rich.

Company
Publication Date
Change
vs. S&P 500 (% points)
Google (Nasdaq: GOOG)

June 26, 2011

21.8%

17

Pricesmart (Nasdaq: PSMT)

June 28, 2011

37.8%

35

Activision Blizzard (Nasdaq: ATVI)

July 15, 2011

1.4%

0

Intuitive Surgical

July 25, 2011

32.5%

33

National Oilwell Varco (NYSE: NOV)

July 28, 2011

(16.8%)

(20)

Coca-Cola

June 21, 2011

15.7%

12

Whole Foods

June 5, 2011

40.9%

41

Amazon

July 12, 2011

(0.9%)

(3)

Apple (Nasdaq: AAPL)

June 30, 2011

72.5%

71

Johnson & Johnson

Aug. 8, 2011

0.1%

(4)

       
Total  

20.5%

18.2

Source: Fool.com

Although the absolute returns offered up have shrunk since last month, they've decreased by far less than the overall market has. By market close yesterday, the "World's Greatest Retirement Portfolio" was outperforming the market by a whopping 18.2 percentage points!

The past month was relatively quiet for the portfolio. Probably most encouraging were the numbers from Activision's release of Diablo III. Though there were some initial hiccups with accessibility to the online game, it's more than understandable once you get a look at how many were trying to log on. Over 3.5 million copies of the game were sold within the first 24 hours of its release!

Whole Foods also came out with earnings that impressed Wall Street. Revenue rose 13.6%, income was up 30.9%, but most important, comparable-store sales were up a whopping 9.5%!

Beyond that, there's one number to keep your eye on in the coming month. PriceSmart will be coming out with its monthly sales figures early on this month. Expect same-store sales to be in the double digits after last month's dip.

Three best buys
Though the aforementioned companies performed admirably well, they didn't make my list for best buys this month. My first nod goes toward Google. I called the company out last month as a best buy for your money, and my thesis remains unchanged. As I explained earlier, I don't mind the potentially dubious share structure to ensure Larry Page and Sergey Brin retain decision-making privileges. As it stands right now, the company is trading for just 17.5 times earnings, only 16 times free cash flow, and it has a PEG ratio of 0.76.

Next on the list is Apple. I don't think it makes much sense for people to be all up in arms over the stock's decline since hitting a high in early April. Let's not forget that today's price of about $577 sits about 66% higher than it did a year ago. But that doesn't mean the stock isn't cheap -- because it is! Who knows if or when it will reach $1,000? But if the world's greatest company is trading for just 14 times earnings, 11 times free cash flow, and has a PEG of 0.63, then it's a screaming buy in my book.

Finally we have National Oilwell Varco. Believe it or not, I actually chose NOV over Apple when I had to decide where to park last month's Roth IRA contribution. My reasoning was actually quite simple: "When I look 10 years into the future, it's much easier for me to see National Oilwell Varco continuing to dominate than it is Apple. There's certainly a good chance that Apple will continue to rule, but in the field of technology, things can change fast."

Three stocks to retire rich?
Of course, here at the Fool, we love getting different opinions. Our top analysts have put together a special free report: "3 Stocks That Will Help You Retire Rich." None of my three favorites from this month are on the list. To find what companies did make it, get your copy of the report today, absolutely free!