IE is safer without Chrome Frame.
Adding Chrome Frame to IE doesn't just gives hackers not one just more surface to attack, it also gives them the glue between IE and Chrome Frame to assault. Yes, IE with Chrome Frame really is incredibly fast, but it's also a lot more vulnerable to malware incursions.
In addition, the combination of Frame and IE must be more unstable than IE alone. As Baker pointed out, when you're running Frame with IE, "your browser has fragmented into multiple rendering engines." That sounds like a recipe for hard-to-fix browser problems to me.
I've liked Google's Chrome Web browser from day one. Over time, I've grown to like it on Windows over both Internet Explorer and Firefox. But, while Chrome Frame shows just how slow IE really is, there's no way I can recommend using it.
Want a faster than fast Web browser? Then download and install Chrome. Bu itself, it's safe enough. But, just skip Chrome Frame. Mixing and matching Web browsers is just asking for trouble.