Intel/Linux boxes are real popular on WHT. I suspect this is true because of the broad based user (and paid) support available.
Depending on your skill-set, or who you will use to admin the server, Sun has some very nice entry servers that will work.
Sun Box with all Sun components:
V100 550Mhz Sparc, 1GB Ram, 2x 40GB drives Raid 1: $1830.00
V100 550Mhz Sparc, 1GB Ram, 2x 120GB drives Raid 1: Not Available
Sun Box with 3rd Party components:
V100 550Mhz Sparc, 1GB Ram, 2x 40GB drives Raid 1: $1230.00
V100 550Mhz Sparc, 1GB Ram, 2x 120GB drives Raid 1: $1380.00
* Sun warranty void using 3rd party components
These prices (I think) are not all that much more than a decent Intel box, and less than some I've seen.
Sun OS is quite a nice system.
The down side is getting sun help is more challenging than getting Linux help. I purposely selected a data center that staff's Sun certified tech's, so that I can get help if I get over my head.
Hope this helps, and doesn't confuse the issue.