I´m looking for a new laptop which I can use for trading (with Ninjatrader).

I have recently seen this one:

Lenovo IdeaPad Z570

Intel Core i7-2670QM, Quad-Core
8 GB RAM
750 GB HD
NVIDIA GeForce GT 540M (2048 MB)

Lenovo IdeaPad Z570 M55B2GE - i7-2670QM 8GB 750GB GT540M Blu-Ray-Brenner!

Looks ok to me and is much cheaper than the Lenovo ThinkPad series.

Any opinions or different suggestions?

Thanks in advance

You won't get the standard Lenovo quality keyboard with these, they have the mainstream chiclet type.
Depends on your typing needs then..
I would also go for a laptop with a SSD, because laptop hard drives are waaaaay too slow to be usable in my opinion.

Slightly off topic :

We've got 3 Lenovos in the household, all with SSDs
.An old T61 that's used as a backup rsync server, and does some Ninja/Visual Studio from time to time.
.A X200s, very small (A4 format), light, lasts 14 hours on battery, you don't have to carry the power supply for the day.
.A 17" W701 used as a desktop computer, with integrated wacom board.

Even with their different sizes, the 3 laptops use the same high quality Lenovo keyboard, so you always have the same typing feel.
Overall they all work very well, don't have useless blinking logos, funky colors, they're black, well built, get the job done.

For each laptop,you can also get the detailed dissassembly guide on Lenovo's site, and buy directly any replacement part ( bezels, etc) directly from Lenovo. I love that.

Go Lenovo !

Thanks for the answer gomi.

Is it only the quality of the keyboard or are there any other disadvantages?

I´m quite unsure what to do? I looked at different lenovo laptops, eg Lenovo ThinkPad L520

They have a dual core cpu (i5-2430M or i5-2450M) and come with 4GB RAM by default.

I don´t know what I really need. I only want to run several NT7 charts with some indicators in COBC=false mode without any issues.. I don´t use the backtesting feature of NT7.

Are there any benefits for me if I choose a i7-2670QM, Quad-Core cpu, 8GB RAM and a NVIDIA GeForce GT 540M (2048 MB) card ?

Beware of the screen, most thinkpads have matte screens, dunno about ideapads, but almost all consumer laptops have glossy screens, this is a deal-breaker for me.
If you can, try to find an IPS screen, they have much larger viewing angles than standard low quality TN laptop screens. But I think you can only find them on premium HP (8560 8760) and Dell M4600 M6600

Concerning the CPU, Ninja is not often multithreaded so you must go for the CPU that has the highest frequencies : 2670QM is 2.2 / Turbo 3.1 GHz, 2450 is 2.5 / Turbo 3.1 so I would go for that last one, it will have better perf than the i7 when only 2 threads are needed.

You don't need any funky high end video card.

Again, if you can find a laptop with a SSD upgrade, go for it, it really, really changes your laptop experience. The difference is waaaaaaayy bigger than a CPU or RAM upgrade.

If you can read french, here's a nice page where are listed all current "good" laptops.
https://www.choixpc.com/portable.htm