Need some advice !

I recently bought a 1997 a4 1.8t quattro that came with a Neuspeed 1 bar chip. A couple of days after I bought the car I had to replace the ECU so now I have no chip at all. The place that fixed the car sent the computer out to a guy to have it looked at and he concluded that i needed a new computer (the Neuspeed chip was never tested to see if it was working correctly or not). The mechanics then told me that i should not put the chip (what they reffered to as NOSPEED) back on the new ECU because they think thats what caused the problem.
Are the mechanics just blaming the after market piece because they dont actually know what the problem is ?
Can a chip actually develope a defect (the guy i bought the car from said it worked well for him)?
From what I read the GIAC or APR are the preffered chips for my car but should I use the Neuspeed seeing as tho I already have it (Money is tight so i probably would not buy another chip)
And the last guestion, Is intallation of the chip difficult? I was thinking of having an Electrical Engineer or technician from my University do it. Is that safe or would that be a stupid thing to do ?

Thanks alot guys !!!