Which province you are in right now?

If it is Ontario, I strongly recommend to get yourself enrolled in a public college.

it is BC,vancouver....when i applied for single entry visa that time I sent my Part time studies acceptance letter as a proof. It seems like no issue otherwise they would have declined my application of single entry on the bases saying i am not doing full time course .

So i guess it shouldn't be an issue if i am holding student visa but doing part time studies and I hope it won't stop me from re entering into canada but I will definately enrolled in a full time course in some private college .

It always makes sense to study in public college rather than private ones, specially, when you are paying same amount of fees.
Private colleges are somewhat cheaper than publics. However, it helps if you are in public college or university when you apply for PR.
As Gurram suggested, you may not face any problem at the time of re-entry into Canada, but it may create problems when you apply for your PR.
If you do not intend to apply for PR then it would not matter where you study.
Hope this helps.

Thanks Gurram and jigz for replying to my posting.....:-) It would definately help me.