Here is a link to some discussions on installing an H700 into a 2950.

http://community.spiceworks.com/topic/149726-dell-poweredge-2950-and-h700-controller

You could install a PERC H700.  It is not supported, but some have reported that it works.  They  haven't mentioned whether or not they were able to simply replace the card in the 2950's "integrated" storage slot or if they had to install it in a rear PCIe slot - since they didn't mention it, I would assume it was able to go in the storage slot.  You WILL need new cables, as the H700 uses the 8087 connectors and the PERC 5/6 uses the 8484.

They aren't very expensive:
http://www.xbyte.com/ProductDesc.aspx?code=CAT_1910_45

Just know that they aren't supported in the 2950, so things aren't guaranteed to go perfectly as planned.

Can I put a couple of PCI-e sata cards in and plug the drives in manually and have no raid?

Generic/third-party cards tend to be more troublesome, but if you do try, just keep in mind that you cannot have a card with individual SATA connectors - you will need one that takes a SAS connection from the backplane.  Otherwise, there is no way to connect the drives to a controller or to separate power (if not the backplane).

I want to use software raid anywhoo

The PERC 5/6/7 do NOT support non-RAID, so any disks connected to them would need to be configured in a RAID array before they could be used.  Drives can be configured individually as single-disk RAID 0's if you wanted to use software RAID, but other than that, you should NOT mix hardware and software RAID.  The H200 controller supports non-RAID/JBOD, so if you are going to do a software RAID, that would be a better choice (and slightly cheaper).

I'm guessing I can't just partition the drives to 2tb each and then be read.

Nope.  It is a hardware addressing limitation on older controllers.  Beyond the controller, 2TB is a DISK limitation requiring the GPT formatting, not just a partition limitation, so depending on how you intend to set this up, keep in mind:  

• in order for a physical disk (or an array/VD) that is larger than 2TB to be seen by the OS, it must be converted to GPT first
• you cannot boot to a GPT disk unless the OS supports it and is installed on a UEFI-enabled system
• the 2950 does NOT support UEFI

So, if you do get a different controller, just remember that your BOOT array/VD/disk cannot be larger than 2TB on the 2950.