brotherhood_of_LAN - 7:29 pm on Apr 6, 2011 (gmt 0)
If you're a WebmasterWorld supporter I'd offer a few public suggestions for hosts in the webhosting issues [webmasterworld.com] forum...
WebmasterWorld recently migrated to a dedicated server using liquidweb as described by Brett here [webmasterworld.com], it looks to be around $250 a month, which is a fairly competitive price but there is cheaper out there. You may just want to take a couple of hours searching and comparing hardware/reputation against price.
Quad core or higher seens to be about right. Most of the time my main concern is hard disk speed and CPU's are rarely maxed out.
I'd expect 8GB as a minimum. Although I've rarely used the CMS's you use, I know they use MySQL. You could dedicate a portion of your memory for MySQL to retain indexes which would speed up queries dramatically.
RAID options seem to be getting more popular and can offer good speed benefit. Disks tend to be the main bottleneck for speed, particularly for database driven apps. Solid state disks offer a lot of benefit though they're rarely offered in 'out in the wild' dedicated servers.
I have a 1Gbps connection and a 10TB limit. If I reach that limit I'm redueced to 10Mbps, which is unlikely. Dedicated servers tend to offer very generous bandwidth allowances and add-ons whereas shared hosting tend to penalise you heavily for going over the limit. 100Mbps connection would be a good start.
Also consider which country you want to be hosted in.
I think your CMS's will benefit most from a RAM increase and a bigger bandwidth pipe. Hopefully that helps a bit.