Pls Help a lost soul to find right graphics card!

Hi, I’ve couple of questions for smart guys like u.

I’ve selected Sapphire Radeon HD 4850 512MB, but I’m confused about which design I should buy. There is a single slot design and a dual slot design by Sapphire (In my country choices are limited). I don’t have any problem with dual slot as my previous graphics card was EVGA 8800GTS 640mb. I’m not fond of over clocking and I think it will void my warranty, so no over clocking. I also don’t mind loud fan noise as long as my card temp is reasonable. The single slot has hit sink covering ram but the dual slot does not have any hit sink over the ram. Will it be a problem? So pls advice.

My another question, is it better to get a 4850 1GB or 512mb. I’m using 19” LCD with 1280x1024 native resolution and I’m not upgrading soon. AFIK I’ll be ok with 512mb, so am I right?

For alternative choice I can go for 8800 Ultra, but 9800GTX or GTX+ is not available here. The most interesting thing is, in my country 9800GT 1GB is slightly more expensive than 4850 512mb! Am I making the right choice by selecting 4850? I’ve read many reviews; from my experience I think 4850 is better than 9800GT & 8800 Ultra. Do u guys agree with me?

I’ve too many questions, I know. But its important for me before I jump as I’m not going to upgrade near future. THX in advance for reading & replying. Any suggestions will be appreciated. THX again

My spec:
E6600 @ 2.4
Intel DG965RY
2X 1GB Ram 667
19” LCD (1280X1024)
Thermaltake purepower 680W PSU
[Air in flow: 1x 120mm fan in the front of casing, 3x 80mm fans left side
Air out flow: 1x 80mm fan back side, 2x fan of the PSU.
Previous graphics card EVGA 8800GTS 640mb ACS3 (70C idle & 88C load)
One & half year old PC]