Porting the old skins into your current project is a fairly straight-forward task. In order to do this, you need to download the source for the controls you purchased. Because the skins are typically packaged in with the assembly, you need the source files to extract the skin manually. Once you have downloaded the source, create a folder in your new project called 'App_Themes' and copy the 'Skins\Blue' folder from the source for the older RadGrid. Next, set the Themes property in your page directive to "Blue" and the Skin property of your RadGrid to "Blue". Finally, set the EnableEmbeddedSkins property of your RadGrid to false. That should be it.
Here's are some screenshots I took to help you. The first is of the .aspx page
, which shows the properties you need to set in your page directive and on your RadGrid. The second is of my solution explorer
, which shows where you should copy the skin files.
You may want to check out the WebBlue skin which is built in to the current RadControls for ASP.NET AJAX. It's very similar to the classic Blue skin, but with a Web 2.0 look and feel. However, if you still need to use the Blue skin, that is still an option.
I hope this was helpful. If you have further questions, please don't hesitate to ask.