Hi, we have a requirement to develop an User Interface which should be able to deploy in Linux as well as Windows XP/7. Please can you help me in with some tips.

There are several good GUI tool kits that are cross-platform for this. One is Wx, and the other is Qt. Qt is the more popular one. Wx may be simpler. I have used both, but Qt is what I have mostly used for professional software development.

FWIW, Qt used to be owned by Nokia, but was spun off a couple of years ago. Before Nokia owned it, it was a small, but popular software vendor. Nokia put a lot of resources into enhancing it, so today it is the most popular high-level GUI development toolkit, capable of handling very complex multi-threading applications. It is very commonly used for stock trading systems (which is where I became familiar with it, in the 2006-2007 time frame), amongst other things such as GUI windowing systems.