Is a Certification from Siemens such as NX Designer Certified Professional (NX) help in boosting your interview prospect? Is a certification from Siemens really worth as it has only one module for NX design certification?

It certainly doesn't hurt! At the very least, it shows a level of dedication on your part and in my book, that accounts for a lot.

As someone that hires, has been a part of the hiring process and/or has worked with and trained a lot of new hires, I have to admit, it doesn't make or break a candidate for me.
If I'm looking for someone with less than 5 years experience, I could honestly care less what software experience you have. I want to see your soft skills; your eagerness to learn; your desire to get out on the manufacturing floor and see how the products are built.
The rest, can be taught and/or will be absorbed with time and experience. Can't teach work ethic though...

If I'm looking for an 'experienced' designer, then again, the software may not mean so much as a good strong fundamental understanding of design for manufacture. If you've used other CAD packages, you'll acclimate quickly soon enough. I personally see a variety of CAD package experience as a plus, not a minus. Most of the guys that know one package, will spend all their time complaining... wondering why package 'B' doesn't work like their beloved package 'A'.

So it really depends where you're at experience wise, because a certification tells me that you can hit the ground running with very little acclimation. That's certainly a 'plus' in most hiring arrangements.

Good luck

The exam can't hurt you, unless it costs a lot of money to take, then you'd have to consider if the expense was worth any potential gain.

SOLIDWORKS has a number of exams that can help add some content to a resume, and I assume the NX certs are the same.

Are there different levels of certification available? Getting the "best" level will stand out more on a resume than an "average" cert which dozens of candidates may have.

The interview process is often conducted in tiers, so having a certification can help you get past the initial screening in a larger company. Then you'll need to be able to demonstrate your skill in the interview by having a portfolio of projects or models you've worked on. Or, at least have a rather impressive sounding/looking resume if you have a good deal of work experience.

More and more companies are placing a larger emphasis on certifications (and I say that having just come out of 6 months of unemployment).
Me telling a company that I'm "good with computers" carries no weight. Showing them my CompTIA A+, Security+, or Network+ certifications go a lot further.

But like cmalco said, you also need to know how to design/manufacture items, and be a good employee that shows up, and contributes.

Thank you for your astute and knowledgeable suggestions.
I would be glad if someone who has taken the certification exam give me in insight.
Thank you in advance.
Let peace prevail :)