Hi Catalin,
The sensor and the lens makes the difference between cameras. With the
FZ38 you have the versatility of a 18x zoom, but the 1/2.33" CCD which
means it's dimensions are 6.13mm x 4.6mm will not be capable to give
you the same definition as a DSLR DX sensor which are 23mm x 15mm
(four times larger).
Here is a nice page for explaining sensor sizes are resolution /
inch :
http://www.photoreview.com.au/tips/buying/unravelling-sensor-sizes.aspx
If you want to go pro, forget megapixels and zoom, buy a DLSR with a
good lens (not the stock one) and start exploring.
I still have my old Nikon D40 but I am looking to buy the newer D5000,
with maybe the 18-105mm VR lens, which is not that expensive as the
18-200mm VR lens (the D5000+18-105mmVR price equals the price of a
18-200mmVR-II lens)
Best regards