Besides the things Duckie mentioned, is your SATA interface in AHCI mode rather than IDE? Changing to AHCI might help somewhat with it's speed, but takes a little more work than just changing the SATA mode to AHCI in the BIOS.
Also, according to the specs and tests I've seen on the X25-V 40GB SSD, it has a rather low sequential write speed, 35MB/s, which could be lower than your HDD's write speed, thus the lower Window Experience score. As Duckie suggested, you can download AS SSD Benchmark (free) and test your SSD with that.
Your problem with the extra volume is odd, I've never used the migration tool so I can't comment on that.
Well, the sequential read speed of the X25-V is likely slower than the C-300, but should be at least comparable to your HDD, and the X-25V's IOP performance should be better than any HDD. But you can subjectively tell how fast your PC is, and if it seems slower than your other drives, that is a shame.
Did you verify that you are using an AHCI driver, since setting the SATA mode to AHCI is not enough to be operating in that mode. In Device Manager, check the driver of the IDE ATA/ATAPI controllers, which must be msahci or iaStor in you loaded the Intel RST driver.
You mentioned that the C-300 SSD crashed? How did it fail, just stopped working or what, I'm just curious.
For space saving tips have a look at post 5 in this thread: http://communities.intel.com/message/115253#115253
In particular if you have a lot of RAM and use hibernation you will struggle on a 40GB drive.
I’d be inclined to do a secure ease and a new install. If the drive does not then show a significant improvement in performance something is wrong, but it will be easier to narrow it down once you have done the above.
If you do a fresh install disconnect all other drives until the installation is complete