Perhaps, but probably only if you bought the HDTV from Walmart as well.I'd suggest HDMI cables from Walmart ~$30-40. In a digital world HDMI, I doubt there would be any visible difference.
Cheap cables will give you poor results as a rule. High-priced esoteric cables won't necessarily buy you the Holy Grail either. Monster Cables are generally overpriced and overhyped for what you get. OEM cables are usually thrown in the box as an afterthought and should be considered throwaway items (literally). You can buy some excellent quality HDMI cables for well under $100 and probably much less. There are some good cable vendors listed over at the AVS Forums that sell quality products at reasonable prices.
Keep in mind how much you invested in your HDTV and decide if you'd rather save a few bucks and buy cheap cables and then consider the weakest link theory. There's not much point in buying a great TV if the cables won't give you the best signal. OTOH, don't give into the marketing ploys of high-end cable manufacturers. IMHO, good quality conductors, excellent shielding, and quality insulating and dielectric materials will give you great results. The rest is mostly hype aimed at your insecurity in the hopes of prying a few extra bucks out of your wallet. The best advice I can give you is to try various brands of cables and see if you can tell the difference.
There is little or no discernible difference between the picture quality viewed from HDMI or component outputs. It would depend mostly on how your monitor processes the two inputs.