A friend and I have started a project using code from another project, that is covered licensed under GPL. We have distributed it freely on our website, and under its download button, we've added a direct download link to the modified source code also for free. At the about section of the application, we have credited the guys who built the original code. Does the fact that we have a different project name violate the terms of the GPL? And also, if we include the original GPLv2 notice from the original app does that help us comply with it? If not, please state exactly what we have to do to comply with the GPL. The code we're using is an older version, released under GPLv2, and that project has been discontinued, and moved to a different one, where they're still developing. We haven't used any of their current coding, which is released under GPLv3.
The GNU General Public License v2 reads:
 You may copy and distribute verbatim copies of the Program's source code as you receive it, in any medium, provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice and disclaimer of warranty; keep intact all the notices that refer to this License and to the absence of any warranty; and give any other recipients of the Program a copy of this License along with the Program.
 You may modify your copy or copies of the Program or any portion of it, thus forming a work based on the Program, and copy and distribute such modifications or work under the terms of Section 1 above, provided that you also meet all of these conditions:
a) You must cause the modified files to carry prominent notices stating that you changed the files and the date of any change.
b) You must cause any work that you distribute or publish, that in whole or in part contains or is derived from the Program or any part thereof, to be licensed as a whole at no charge to all third parties under the terms of this License.
That means that when your project is based on GPLv2 software, it also has to be released under GPLv2.
For that reason the GPL is often criticized for being a "viral" license - using GPL code in a project "infects" it with the GPL and prohibits you from releasing it under a different license.
To do so you have to:
- Make sure the GPL in text form is included in the distribution of the program and make clear that these license conditions apply to your program
- Leave any copyright or warranty notices of the other authors intact
- Publish the sourcecode
- Add a change date as a comment to each source file you edit
You avoid a GPL violation by simply adhering to the GPL license terms. From what you describe (your source is available, license terms are still GPLv2, source acknowledged) you've done enough.
You don't need to include the original GPLv2 notice; your own version is sufficient. However, you do need to acknowledge the copyright of the initial contributors.
Using a new project name is no violation of the GPL. It's in fact the norm for forks of OSS projects, and might be required under trademark law.