While waiting for my Belkin antenna to arrive, I rotated my desktop to bring the existing antenna in line with the router on the other end of the house. I immediately got an improvement in signal from - low to very good.

When my Belkin antenna arrived, I was surprised to see that it was of the same size as the original antenna supplied with the PCI card! The only advantage is that it is now connected with a cable. So now you can place it anywhere close to the desktop. But the reception remained approximately the same. See description from Belkin below:
http://catalog.belkin.com/IWCatProductPage.process?Merchant_Id=1&Product_Id=126498

Here is how you should evaluate if you need this product:

a) Draw an imaginary line between the fixed antenna and the router. Now remove as many obstructions as possible on this line. The CPU itself maybe an obstruction. If possible rotate the CPU.If this helps then the desktop antenna will probably help.

b) Another test to determine if the desktop antenna will help or not is to place a wireless laptop close to the desktop and compare its reception with the desktop. If the two are significantly different then the desktop antenna would help.

Overall, donot expect a miraculous improvement in signal strength. The antenna only helps you to place itself in a better location. You could do the same by moving or relocating your desktop. Good Luck!

Enter the Belkin antenna. After removing the network card's antenna and attaching the Belkin, signal strength more than quadrupled, to 85%. That makes the internet connection usable again.

I would have rated it a five if it would have given me 100% signal. What's the problem? The card? Planetary alignment? Who knows... But the Belkin was worth it!