1) You must ask yourself: do I want a 'slim-line' type unit (for portability and smaller footprint), or can I live with bulkier desktop unit mounted in an external enclosure.
2) Slimline units are 'cool' but those are usually more fragile and harder to get. Also, you have to decide whether you want DVD reader + CD-RW burner combo (usually under £100 for USB only; over £100 for USB + FireWire ~ however burning CDs should work just fine with USB; also see point 4), or DVD burner (that will also do CD-RW; those will be however in 'over £250' range)
3) I personally use (with desktop setup) external IDE/ATAPI to USB2/FireWire box hosting a regular desktop DVD burner. The enclosure has build in power supply (not much to misplace but power cable), small fan and on/off switch. It is based on Prolific chipset (does not require loading drivers under 2k or XP ~ not sure about Me). You can buy those for about $30 in USB2 only, or about $40 for USB2 + FireWire. All you need than is any half decent drive of your choosing (you can hunt down a 4x DVD burners for under $80; CD-RW + DVD-ROMs are even cheaper)
4) Please note that 4-year old notebook might utilize the original incarnation of USB (as opposed to faster USB2) which may support burning CD-Rs only at low(er) speed. For burning DVDs you will definitively need USB2. Watching DVD movies should work fine on any USB version.
If you decide to upgrade (via CardBus card) to USB2, I would actually strongly recommend FireWire interface instead.