3870 for Starcraft II
 

The guy's presently using a integrated 6100 or something like that. Is a 3870 enough or should the sights be set a little higher?

It's a lower end Dell system so it probably only has a 300-350W PSU. Would a 5770 be to much?

Although a 5770 is a good GPU, the min power supply is 450W.

Most 5xxx series ATI cards need 400W+. If the system it's going in has a standard 24 pin atx power connector, you could always get a new power supply for it.. but by the sounds of things, you'd be overkilling the current hardware with the newer GPU.

I've read that Dell PSUs are a beast, so it should definitely be able to handle the mid-range GPUs. However unless he's getting a 3870 for cheap, I'd suggest a 5670 or 4830. I think those are the better options as they're newer and can future proof his comp a bit.

The 3870 could probably be had for $50 but he wouldn't be against getting a new PSU as well if the framerates are there.

if its a good one, i.e. delta or such, it will take an 8800gt, given cpu is not a hog itself to booth with. best investment for that pc.

I think I've convinced him to go with a GT 240

NCIX.com - Buy MSI GT 240 550MHZ 1GB 1580MHZ DDR3 PCI-E VGA DVI HDMI HDCP Video Card - VN240GT-MD1G In Canada.

No PSU worries there.

The PSU will be enough to handle any reasonable video card, so that really isn't an issue. But a GT 240 would be a good choice.

3870 is good enough... i'm currently using one, and i've played sc2 with high settings.

Stick with the 3870. I've had friends play on integrated graphics of all things with SC2. A 3870 should be more than enough for it