CPU upgrade questions

I own a Lenovo R61 Thinkpad with a Intel® Celeron(R) CPU 540 @ 1.86GHz. Im in the process of upgrading it so i took apart an old dell desktop computer and took out an intel pentium 4 processor @ 3.00 GHz. Can I use this processor in my laptop? also its 32-bit running ubuntu 14.10. would this output to much heat as well? please help

No. Desktop and laptop processors are different (desktops are larger). Even if you could, your laptop would have to support that specific CPU.

thanks! Would you suggest to me a better CPU?

Save up for a new laptop.

If you feel like it, your processor should be able to be switched out with a core 2 duo. Most mobile core 2 duo's are relatively cheap (a few dollars on ebay)