Computer hire definitely comes under sec 194I as hire of plant and machinery which is chargeeable to TDS @ 10% for FY 2006-2007. So no question of TDS deduction u/s 194C at all.
Mere execution of contract between parties would not change the substance of the transaction. U would required to see substance of transaction before TDS deduction. Contract is of the different types and one has too look into the nature anf type of contract. If contract is for some execution of some work then it would be coe under 194C. if it is for hiring or leasing then would come under 194I. Based on the circumstances of the case, we have to determine which section would be applied..