As a beginner with a relatively cheap 500mmx114mm (f4.3) newtonian, what
am I
likely to be able to see well?

You'll enjoy starting with the moon, Jupiter and Saturn. Then branch out to
the Messier objects.

The optics seem pretty good, though with the 2 eyepieces I have (17 and
10mm
plossl's), the top magnification I can get it 50x :-(

Now I do have a 2x Barlow, and a 4mm Plossl arriving soon, which will give
me a
a range of magnifications of 29x, 50x, 125x, (and 58x, 100x, and 250x
with the
barlow). I know this 250x exceeds the 228 theoretical limit, but I'm
hoping it
will give a reasonable view of some things... I probably should have got a
6mm
instead, but hey ho, I'm just starting out, and I get to keep the lenses
if I
sell the scope...

You may find the 125x is as high as you can go, but you'll have to try it to
find out.

Am I going to need filters to see nebulae? What magnification is best to
get
good views of jupiter and pluto?

Nebula filters can help, especially if you live in the city. However they
are not much help with galaxies or reflective nebula.

I think I'm more interested in the nebulae + galaxy type observations, is
that
what are called 'deep-sky obects'?

Yes.

Thanks all for your input - and please look out for my other thread
regarding my
next scope purchase!!!

Enjoy the scope and let us know what you find!

Clear Skies

Chuck Taylor
Do you observe the moon?
Try the Lunar Observing Group
http://groups.yahoo.com/group/lunar-observing/
Lunar Picture of the Day http://www.lpod.org/
************************************

Cheers,

CandT