I agree you should take out the word "birthday" and don't apologize for not having cable. Otherwise its a great invite! Looks totally normal (and sounds fun!)
And while there is disagreement, I for one think its awesome for adults to host their birthday parties, in exactly the way you are doing. Have fun!
And here's a few party tips since you are inexperienced:
Start making ice now. make a tray or two, and dump into a bag or bowl and store in the freezer, repeat daily. You can never have too much ice at a party, but you can definitely not have enough.
Put snacks in various places throughout the room, like one bowl on the coffee table, one on an end table, etc not all on one big table. This encourages people to sit around the room in different places. You can always move them if you find people in one area are eating more.
Put drinks on a totally different table then food. Again this encourages movement.
When tidying up, if you have a big box, stuff things you can't find a good discreet home for in the box. Top with a board (or flip the box over) and then cover the whole thing with a pretty piece of fabric - voila! Storage and an extra table for drinks!
Have a plan where you want people to put their bags (and coats if its coat weather in your area).
A super cheap fun way to decorate: colored lights. String colored holiday lights around or even just get some colored light bulbs and put them in your lamps. Remember red, orange and pink are flattering and make people look more attractive, blue and green are not flattering, stay away from those colors. A red silk scarf draped over a lamp can also give this effect and looks nice.