Need Graphics Card advice

Since im a bit of a noob at GFX cards, here's my question.


This friday i'll be purchasing a new GFX card to upgrade since my current old one died (im currently using the on-boards chipset), the one I was going to buy expired from ebay, so im looking at two others right now, one has more GFX memory, the other has a superior clock speed, here they are.

Better memory:

NVIDIA GEFORCE 9400GT 1GB PCI-EX 1024MB GRAPHICS CARD on eBay, also Graphics Video Cards, Graphics, Video TV Cards, Desktop PC Components, Computing (end time 09-Apr-09 12:21:27 BST)


Better Memory Clock Speed:

ZOTAC NVIDIA GEFORCE 9500 GT 512MB GRAPHICS CARD on eBay, also Graphics Video Cards, Graphics, Video TV Cards, Desktop PC Components, Computing (end time 20-Apr-09 12:41:03 BST)


So my question is, what significance does clock speed have, ok to save the mumbo jumbo, What's it for?

To help with the choosing, the reason im upgrading is to help reduce the frame lag/slowdown I get when there's alot going on in certain PC games.


Thanks

More memory in the 9400 might mean some slightly better frame rates in some games than if it had 512, but it probably won't hide the fact that the 9500 is still going to be the better card. Neither will be top of the line or anything, but the 9500 should be noticeably better more often than not.

Personally would avoid eBay and go for something from a quality site such as overclockers.co.uk - often you'll get a solid warranty and a more sensible returns policy. I personally avoid eBay for anything I buy for my PC.

EDIT: What 'certain PC games' are you talking about? That would give everyone a much better idea of what you should be looking at.

Well it's hard to be specific, since I play a wide variety, PC games, MMO's etc



Mainly im looking to which will help better improve the overall smoothness of the games on PC.

Spend a little bit more and get something along these lines:
Best PCIe Card: $60 To $90 - Review Tom's Hardware : Best Graphics Cards For The Money: March '09

You don't really need 1 GB video RAM on a low-end card like those you suggested. But yeah, ATI delivers a lot of bang for the buck these days :p.