For throwing around a few movie files and streaming the odd YouTube video? Probably not. But in general terms Intel NICs are by far superior, especially dedicated cards with proper offloading etc. I'd always favour Intel onboard over Realtek, but in practice I just grab an Intel PCIe server card (e.g. Pro 1000 MT) from eBay and use that anyway. It's also a factor if you use BSD, Linux or other OS beyond Windows. The drivers for proper Intel NICs are far superior and better supported for heavy workloads under BSD (pfSense etc) or Linux (IPFire, desktop systems etc) than Realtek et al. As a consequence you'll get more consistent - and higher - throughput from Intel than you will anything else.