I am new to this so please be delicate with me...

I own a Yamaha rxv-2500 and am upgrading speakers with Paradigm reference 40's and ADP 470's. (I have not thought about which Sub Yet. Can I just use monster cable or should I use something from River cable or ????

Let me give you some advice, this is a hooby that is very dangerous. Be careful, very very careful.

I would always suggest first doing a search in the threads on the subject you are interested in, then asking the question you can't seem to answer. There are great people here that love music and always give great advice. There are also those who seem to have a bone to pick. Pableson gave you a good start but since these things are subjective to your ears, there is no definative answer. You can try a few things used and see what you like. I started off with Monster, then changed about 10 times in the last five years. You have to find what you like and not be afraid to make a mistake or two along the way. Good luck.
Pableson - what rubbish. That does nothing to help the person who asked the question. Just because something cannot be measured doesn't mean it is not true.

Being new to this insane hobby makes responding to the question a little more difficult, because we probably don't have a mutual point of reference. Unless a person is tone deaf, every cable sounds different. Some people have not been trained enough to hear a difference. That is not an insult, it's the same as a master mechanic who can hear an engine problem in a vehicle driving past him.

The only way to get anything other than the typical "buy __________ brand cables, because they're my favorite" is to get out there and listen to cables. Sorry I can't impart some magical level of understanding upon you, but it's something you have to do yourself.
Dr R.C. Brockhaus
YES, standard 12ga copper stranded Monster will be perfectly adequate for your application. Buy it, hook it up, and spend the rest of your time and hard-earned money on music!
I would definitely start with cabling that is affordable. Nothing wrong with Monster, plus you can find it at your local Circuit City and Best Buy. Hook it up and enjoy it. The Paradigms are nice speakers. Hopefully your quest will end there. Have fun!