question in using heparin as an anti-coagulation - (Oct/25/2007 )

Hi!
I have collected 10 human blood samples anti-coagulated by heparin. I have known that this substance can only work within 48 hours, but I can not treat them right now. Please tell me is there anyway I can store these samples?
Previously I always use EDTA (not heparin) and the samples can be stored up to years. Can I just add EDTA into the samples (which already contains heparin)?
Thanks a lot.

yes, you can.

can you explain it more specific for me please? this is the first time I handle samples with heparin so I really am confused (I will extract DNA from the WBC and use them for PCR). I also read that heparin can affect PCR, so is there anyway to reduce the effect?
Thank you.