How to configure an Operating system with my PC?

I got a Lenovo Thinkpad T61 without an operating system, and without a recovery partition intact. I also did not have a Windows Vista OS disc, which is what the T61 runs on, so I got myself a set of Windows 7 Home Premium recovery discs I made from my desktop, and used that instead. Now the computer works, but I have a few issues:

1. The T61 now thinks it's an Acer computer with all the Acer files and all that, so basically right now this is an Acer computer inside a Lenovo machine.

2. System doesn't run properly (things crash regularly, webpages don't open, lags everytime I try to click anything, even windows explorer)

My hoped result is to have a real Thinkpad computer that works like a Thinkpad with Thinkpad files and drivers on it, not a Thinkpad computer with a bunch of Acer on it. Any fixes?

I'm sure it would be better to use a generic copy of windows not intended for any specific model, but in any case you should probably at least get hold of some motherboard drivers and so on from a lenovo support site and apply those, that may help

http://support.lenovo.com/...migr-67818