Will the HD4850 suffice, or should I spend the extra $$ on the HD4870?

I would be running at 1680x1050 w/ a C2D E8400. The games I really want to run maxed out are Mass Effect, Oblivion, Far Cr2, and X3: Terran Conflict. I'm trying to save a bit of cash by getting a 4850, but is the extra $100 worth it to get the 4870? Is there that much of a performance jump?

Also, this is the build I am about to buy:

Antec Three Hundred Black Steel ATX Mid Tower Computer Case - Retail

GIGABYTE GA-EP45-UD3R LGA 775 Intel P45 ATX Intel Motherboard - Retail

SAPPHIRE 100242L Radeon HD 4850 512MB 256-bit GDDR3 PCI Express 2.0 x16 HDCP Ready CrossFire Supported Video Card - Retail

OCZ StealthXStream OCZ500SXS 500W ATX12V / EPS12V Active PFC Power Supply - Retail

Intel Core 2 Duo E8400 Wolfdale 3.0GHz LGA 775 65W Dual-Core Processor Model BX80570E8400 - Retail

G.SKILL 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 1066 (PC2 8500) Dual Channel Kit Desktop Memory Model F2-8500CL5D-2GBPK - Retail

Seagate Barracuda 7200.10 ST3400620AS 400GB 7200 RPM SATA 3.0Gb/s Hard Drive - OEM

SAMSUNG 22X DVD±R DVD Burner with LightScribe Black SATA Model SH-S223Q - OEM

I'm pretty sure this will run everything I want at maxed settings, but let me know if I'm wrong. Thanks!

I would get that 4870 for 1680x1050. I don't think a 4850 is enough for Far Cry 2 maxed out from what I've seen.

Do you want to run with 4xAA?

The HD4870 is probably going to offer significantly better performance in the long run at that resolution.

I'd also avoid the StealthXStream and GameXStream line of power supplies. Too many users have had problems with them, and tests have show than their +12v rail is subject to excessive ripple under heavy load.

I'd also get 4GB of RAM - you can get that for around $20 more than that 2x1GB kit if you stick with DDR2 800, which is a nice upgrade given the price.

well gues ill sell my hd4850's soon an d get two 4870'sNeo_revolution7

The value of hardware drops so fast that youll lose money. I got lucky to sell my 4850s for $270. Its probably just because of the custom fan profile flashed onto the bios. I got alot of offers for $200 shipped.