It does say in the specs below that
memory capacity is 4 Gb. I'd definitely look around. Nearly two years ago I put together a DAW with a Gigabyte system board with a PCI slot and 32 Mb capacity, although I "only" installed 16.
My DAW (general specs below) was closely based on that of another forum member, who got it from
iBuyPower. Their systems are intended for gamers, but with the addition of the sound card of your choice make first-rate DAWs. They are burned in for 72 hours before shipping and guaranteed, IIRC (I'm checked their site as I write), for 3 years. It would be hard to build a system cheaper, and you won't get that guarantee anywhere else.
HTH,
Richard
ETA: I just checked, and I was right. They come with a standard three-year labor, one-year parts warranty, which can be extend to four or five years. They are also highly customizable. Some systems can be bought off the shelf and shipped immediately; others will take longer, depending on the degree of customization.