Computer recommendations for SDR

I've been bitten by the SDR bug.

Here's my setup:



(2) NooElec NESDR (R820T) dongles

(1) Ham It Up v1.2 Upconverter (125 MHz LO)

And an old Dell Dimension 2400 (P4, 2.8 GHZ) running SDR# which is the weak link :)



Ideally I'd like to use multiple dongles on the same machine. I see that members on here have run up to 7 dongles at a time. I'd like to do something similar without breaking the bank for a different computer. Does one need to spend over $1000 on a computer to use 7 dongles?



RTL-SDR.com has a guy running 7 dongles on an EKB311 Android TV box. I wish I could find more info and support on something similar....



I'm thinking that running 4 dongles at a time would do the trick. I'd like to monitor 4 HF bands at once instead of spinning the dial/changing bands on my Yaesu FT840 so much.

I plan to get more SDR dongles, splitters, LNA, connectors, and a powered USB hub. Getting all that working is easy. My biggest challenge is sizing an appropriate computer.



I'm open to new/used/upgradeable PC's, Mini-PC's, Thin Clients, etc. Windows XP, 7, and various Linux OS are not a problem. Upgrading hardware/firmware is easy.



What's your experiences/recommendations?



Thanks in advance!

Mick