If your tv does in fact support 1080p you should be running it at 1080p (that's 1920x1080 pixels) @ 60 frames a second, or 60hz.  (this is in the XMB)

Do you know what your display's model number is, so we can look it up on the net?

Yeah my tv's model number is  LA46A750 that should come up as a samsung series 7- 46" Lcd full Hd- I know it does 1080p and that its full Hd- but yeah you have a look at the model and tell me what you think? This is honestly whats had me goin all week- just being so angry- im goin to find out tomorrow whether its the cable or not- but im so confused cos some ppl have been saying " Dont pay $100 for a cable- the $5 cables do the same thing? And they have been saying that 1.3 HDMI cables will do 1080p and it says that they will- but mine wont- im thinkin cos the new ones 1.3 A- maybe thats the difference.... Im confused and tired!!!! I just want to thank everyone again for the help- you all rock!

It's probably not the cable.  Any HDMI cable should be able to push 1080p video.  More likely it's some sort of handshake issue between the PS3 and the TV, with it being one of those 100hz capable tv's.  The only thing I can think of is to try all of your HDMI ports with all of your screen refresh (hertz) settings on each one.  Make sure you try 60hz on every one.   Sorry I can't help more though.

Have you tried doing some google searching to figure out if more people have had this problem?  You could also talk with Samsung tech support to see if they know of any PS3 issues.

Yeah ive spoken to Samsung and they pretty much just scratched their balls and went "Huh?- and yeah ive tried all the ports now, not sure if ive tried all the ports with the re set ( pretty sure i have) But ill try them all again to just be sure! And yeah ive done heaps of research on the net about this and the only thing im findin is nonesense about cables and ppl with xboxes having the same issue..Joined the Ps3 forum throu the Ps3 site the other day and posted my issue- but so far ive had nothing back- i guess if i dont get nething back at all ill just start bad mouthing sony- Yeah just wanna thank you for all ur help neways and yeah as i said before one of these companies is goin to end up with either the ps3 or the tv throu their head office windows!!!

K just wanted to update everyone thats helped me- turned out to be a HDMI cable issue- which was an easy fix... Apparently so far on the market there is 18 different HDMI cables and thats not including brands of cables either and yeah we needed to upgrade ours as it was over a year old... Neways thanks for all the help guys, you all totally rocked!

Glad you got it fixed, was just about to suggest is it the hdmi cable.

Honest i was