The current card runs a 4.5 on Vista Aero performance and 4.1 (was 4.2 on the previous ATI drivers) for gaming, the rest of the system runs at 5.5 for processor, 5.9 for RAM and 5.8 for disk.
I'm very satisfied with the performance/price/reliability mix of the system. It's been solid, with no software issues and generally never gets rebooted for months, running 24x7.
I spec'd the machine as follows :
530s Inspiron (biggest mistake was buying the low profile case version instead of the 531)
Processor : Intel Core 2 Duo E6750 @ 2.66Ghz
RAM : 4 x 1GB
Internal Disk : 2 x Seagate Barracuda ST3320820AS. SATA 3Gb/s 7200RPM 320GB Drives
External Disk : 1 x Iomega 1TB USB2 drive
Graphics : 1 x Radeon X1300 PRO 256MB running dual head with
Screens : 2 x Dell 2407WFP-HC DVI 24inch LCD flat panels
Optical Drive : Hitachi-LG GSA-H31N DVD+-RW dual layer
SATA Controller: 2 x Intel ICH9 SATA controllers (2926 2 port & 2920 4 port)
Ethernet : Intel 82562V Gig Ethernet
Running Dell Firmware - 1.0.12
Running OS : Vista Ultimate 64bit Service Pack 1.
Although on the Dell website, this system has no 64Bit drivers available for it, the Intel, ATI websites and Microsoft Vista 64 disk has all the support the system needs to happily run in 64bit mode.