I have a Linksys WRT54G v1 which would be among the faster of the older routers, and I've measured around 16 Mb/s upload/download throughput through the WAN port via SPI. (Using DD-WRT firmware. IIRC, I obtained similar results earlier with Linksys firmware, but I don't recall for sure that I used the Linksys firmware then). Moreover, this bandwidth is split between upload and download; when upload and downloads are simultaneously active, the upload or download throttle downwards so that the total throughput is around 16 Mb/s. So some such older gear certainly does not do 25 Mb/s.
Note that Tom's measured this router as 20 Mb/s. I like my number better because that's what I see consistently, using tests that I personally trust. Tom's is in the ballpark though.
Originally posted by: Destinova
"Any recommendations for a router than will not bottleneck a connection that could potentially see a 25Mbps throughput?"
I can recommend the DGL-4300 / DGL-4100 based on personal experience. I have a DGL-4300 (my Linksys usually runs a wireless bridge; the D-Link is my main router). It's a good fast, stable, functional router. I and most other owners' reports I read say that they're happy with it. I haven't tested the WAN throughput myself (mostly because my internet service isn't fast, and because I don't want to disconnect it from my network, but I could do that I guess), but the general reports are good.
If I was shopping now, I admit I'd be tempted to get the DIR-655. Caveats are price and likelihood of issues with the draft 802.11n. Risky and costly, but that's the bleeding edge..
If I was on a low budget, or trying to get buy with something cheap for now, I'd consider the Airlink (~$25).
Alternatively there's the Linksys WRT54G
L. This is often recommended for the functionality you can get with 3rd-party firmware such as DD-WRT. I'd actually recommend the similar Buffalo units that appear on DD-WRT's recommended hardware list first. Tom's measures the WRT54GL v1 at around 50 Mb/s, which should be enough for the 25 Mb/s WAN limit.