"Dell does not give a warranty guarantee protection for:
* damage caused by incorrect installation, use, modifications or repair by any unauthorised 3rd party or yourself;
* damage caused by any party (except Dell) or other external force;
* fitness for any particular purpose;
* 3rd Party Products, Software and IM specified by you. You will receive the warranty or licence for these products directly from their manufacturer or licensor;
* any instruction given by you and correctly performed by Dell."
As you needed to install drivers it looks like section one covers this, most if not all PC suppliers will have a similar clause. They simply don't cover repairs necesitated by user damage and modification soft or hardware.
The problem appears to be that your expectations exceeded the reality and given the fact that you can't remember the details and haven't kept a copy of the Terms and conditions, I don't think there's really anything helpful that forum members can offer. Caveat emptor, sorry.