Yes, it'll be an improvement, but not by very much as it has DDR2 memory. If you can find one for similar money with DDR3 memory, then it may be worth going for.
Note that the card needs a 6pin PCI-E power connector from the PSU to run.
If you're thinking of getting a better one solely for gaming & at a relatively low price, a HD 4670 for ~£53 click here, may be a better choice. This does not require a 6pin connector, & will work with most 350W or higher PSUs.
If you're not upgrading for gaming, then it would be best to stick with your current, passively-cooled, silent card that's more than sufficient for most, if not all, other tasks. G