those cards will work fine, you just have to know which riser card you have in the system, PCI-E or PCI-X. 
I am looking for a list of compatible Network adapters that will work with a R1850. In particular, I would like to know if the Intel® PRO/1000 PT Dual Port Server Adapter or Intel® PRO/1000 PT Quad Port Server Adapter will work on this server. A reference link would be good enough.   We got this server a while back and it has a network adapter compatible with Server 2008 but we need a network adapter that compatible with Server 2008 R2 now.   Michael
R1850 Compatible Network Adapters