PCIE 1.0

Generally, PCI-e 2.0 add-on cards can function in PCI-e 1.0 or 1.1 motherboards. There are some exceptions, but I don't think the GTS 250 is one of them. The GTS 250 should work.

If you have a PCI-E slot, it should work, as long as you have PCI-E power connectors to use from your PSU.

Yep i have a Vantec ionn2 600w psu

+1 for everybody, but don't you think the 700W is a little overkill for one 250?

In short: Yes. Given that you have the prerequisites to use the GTS 250, then you can use it without issue.