Are "good" cables needed for vintage system?

I have just put together a very inexpensive 2 channel semi vintage system. I Have maybe $700.00 in it total. It consists of a NAD 1020b pre, NAD 2155 power, Pioneer PL-112 TT with shure M97xe cart, sony HD dvd player to use as a CD player for now, and it all comes to life through a set of Pioneer HPM 150's. I'm running crapshack cables right now, and I'm wondering if upgrading the cables is worth it on this old gear? Surprisingly I do enjoy the sound I'm getting to a "point". But that's why I'm wondering about upgrading cables. Can I get it past that "point"? As you might have guessed, I'm not going to spend much on cabling, but if it'll help, I'll start serching for used stuff.
Any ideas on this thought guys??
What cables would you recomend?

Thanks for you time,
Shawn