It all depends on what slot your current CPU rests in as well as your power supply's rating. Research a quad-core CPU and note the slot type and how much power it draws. Then take a look at your system. CPU-Z is a free tool that scans your system and gives the specification (CPU slot, type of RAM, etc). You may want to upgrade your power supply to one of a higher wattage even if the new CPU is within its power range, for future upgrade potential!
Do not listen to Insomniac001, as his comments regarding chipsets and BIOS are laughable. Do listen to Al Hill, as he is an Intel professional.
I will give Al Hill's advice in a different way. Find the user's manual (or owner's manual or maintenance manual) for your PC. It will contain a list of supported CPUs. Another option is to search for a list of supported CPUs on the PC vendor's website. That is the list of CPUs from which you can choose. That way you will not have to worry about the socket (I believe Insomniac001 refers to sockets as slots).
And, as Al Hill noted, the BIOS must be compatible with your new CPU. This means that the BIOS must include support for your new CPU. You can read the release notes for available BIOS to see which one added support for your new CPU. And this BIOS must be installed before you attempt to use the new CPU, otherwise the PC will not start. You may already have the necessary BIOS installed in your PC, but don't assume. Your vendor may state the required BIOS for each CPU in its list of supported CPUs, but then again it may not.
Thank you for contacting the Intel® Communities.
The information provided by paramountain regarding find the compatible processors is very accurate.
Let me provide you with some guidance to get a better processor or quad core processor as you were asking, lets do the following:
1. Access and look for the first model.
2. Hit the "Compare" button at the right side of the page.
3. Look for the second processor and do the same as step 2.
4. Hit the "Compare Specifications" button.
5. Check the different features or specifications for each processor to see which could comply with your needs.
Do not hesitate to advise the Intel® Communities if you encounter with any additional or new inquiries.