When I make a call on a stock, I want it to mean something. I want to keep track of that call and know when I've hit a home run and when I've whiffed. As a result, over the past five years, most of the stock ideas I've offered to readers have been tracked in my Motley Fool CAPS portfolio.

Late last month, I started the process of reviewing some of my longest-running picks to see whether they're still good investments or in desperate need of the boot. Today, I'm going to pick up where I left off and take a look at five more stocks.

USG (NYSE: USG)
Admittedly, I was initially led to this pick by Warren Buffett after Berkshire Hathaway (NYSE: BRK-A)(NYSE: BRK-B) bought a fairly sizable chunk of the company. But as I dug in with my research, I liked the fact that although the company is selling a commoditized product -- largely gypsum drywall -- it had strong brands that helped differentiate its offerings. Unfortunately, when the housing market that it relies on absolutely collapsed, brand or not, the company's results were clobbered.

My thumbs-up on USG back in early 2007 is a complete disaster today. But is it worth sticking with it? Wiser investors than I say yes -- Berkshire has held on to its stake, Prem Watsa at Fairfax Financial has held a significant chunk since late 2008, and the sharp folks at Evercore Partners started buying last year -- but it's high time for me to bid it adieu. What was once a bet on a branded building-materials company not getting clobbered by a real estate softening is now a gamble on an overlevered, unprofitable, cash-flow-negative housing-market supplier in a brutal housing market. It could come back, but I won't be there with it.

News Corp. (Nasdaq: NWS)
As if I'm working on a theme here, I was led to News Corp. by another one of my favorite investors -- Baupost Group founder Seth Klarman. The stock has fallen since my early 2007 thumbs-up, and the company's profits haven't really gained much ground, either. Today, I think the stock could be slightly undervalued, but I'm going to give it the boot anyway. Why? After the recent wave of scandals, I'm not keen on sticking with the company and its management team. I'm generally more inclined to be a buyer when a company has a storm cloud over it, but management's failings and the lack of a serious discount on the stock makes me feel A-OK cutting this one loose.

Mueller Water Products (NYSE: MWA)
The thesis here was very compelling. The water infrastructure in the U.S. is old and in bad shape. Mueller is a leading manufacturer of water infrastructure products like valves and fire hydrants. Therefore, Mueller would reap a windfall as municipalities upgrade their long-suffering water equipment. I gave Mueller's stock a thumbs-up back in 2007.

Fast-forward four years, and there has been no such windfall for Mueller. Worse, many municipalities are in lousy financial positions and in no situation to take on big water infrastructure projects. Will the windfall still come at some point? Maybe, but in the meantime, the company is not profitable and, though it's been paying down debt, it still carries a very significant debt load. Some investors may want to stick around, but I've seen enough.

Nautilus (NYSE: NLS)
I'm going to be perfectly honest. I don't remember why in the world I added Nautilus to my CAPS portfolio. The company behind the Nautilus and Bowflex lines of fitness products was already struggling when I gave its stock a thumbs-up in 2008, and it continues to struggle today. To be sure, the company has made progress, as it's reduced its operating loss from $12.8 million in 2008 to just $1.8 million over the past 12 months. But it's still not showing a profit, nor is it currently churning out positive cash flow. Add to that the fact that this isn't a business that I think has much of a competitive edge, and it becomes an easy boot.

NVIDIA (Nasdaq: NVDA)
Let me start by saying that I wish I had been looking back at this stock earlier in the year when NVIDIA was up above $25. Woulda, coulda, shoulda – oh, well. But here we are today, with the stock close to double the price that it traded at when I gave it a thumbs-up in early 2009. It's also at the upper end of the valuation range that I gave it when I dug in on valuation a year ago. I think NVIDIA is a fine company -- as do my fellow Fools at Motley Fool Stock Advisor, where it's an active recommendation -- but it's not a company that I'm dying to own for the long term, because of the cutthroat, fast-evolving market that it plays in. For that reason, I'm happy to take a big gain and keep an eye on it in case Mr. Market gets crazy again and decides to sell the stock at a big discount.

Now what?
I don't think the five stocks above are great buys right now, but my fellow Fools have identified five other stocks that they think are great buys. In fact, they're so positive about these stocks that The Motley Fool invested real money in them. To find out what they are, check out this free special report: "5 Stocks The Motley Fool Owns -- And You Should Too."