I almost bought a Marcy cheap bench with lat pulldown and preacher attachment last year. I asked the salesman how much the lat thing could hold and he said "ohhhh, loads, never mind that, just buy it" or words to that effect
needless to say I didn't, checked it out on the 'net and found out it could only handle 20or30kg, I forget. not nearly enough anyway.
you'd be much better off buying a cheap dumbell bench, eg the York one, which I have put 200+kg on without a problem, and a chin bar, for about 50 quid for both.
OR, if you're serious about lifting, splash out on a good heavy duty bench, eg Bodysolid, and a chin bar, and you're set for life
I did the former, but a year on I wish I'd done the latter.