I have two samples with me. they are CEL files. image file form microarray studies. I would like to analyse and determine the differentially expressed genes . Now my question is anybody please tel me how can I analyse the microarray CEL files?

And is there any free software available for this kind of analysis?

Thank you
If you have only two samples without replication it is not possible to perform a proper DE analysis using statistical tests. The only thing you can do is rank the genes by absolute differences between those two samples, extracting the top N genes and use them for further evaluation.